First: Picking a song.
This is easy and hard at the same time. Choose a song that won't annoy you even if you have to hear it like 1000 times during the mapping process.



Second: Make a scheme and analyze the parts your song consists of.

Pretty much any song works with repitions of certain parts therefore it's helpful to know when which part is played and how often each part is played.
This information is valuable as it allows for the most general planning of your beatmap.
This includes planning breaks and relations between parts to get emphasis on the right spots. It might also help deciding where to cut your mp3 if you want a shorter version.

Examples how this might look for different songs(this is what I got after hearing through each song 2 or 3 times); please note that my "0" is when the music starts and please hear at least through the Queen-song as I'll use it multiple times as an example in later parts:








I tried to use popular songs so you can go to YouTube or your CD-player, play the song and recognize each part.

For those that aren't acquainted with musictheory at all:
A letter like A resembles a distinctive theme of the music. If there's nothing else and you got 2 A in a song then these are the same aside from the last notes that might differ due to connecting to different passages.
If there's something like A' then it means that we have essentially A but there is a noticeable variation from the theme.(In "Goodbye My Lover" the singer's rhythm in A' is distinctive from A).
You can see that the same parts also have the same time(might vary slightly in the examples cause i wasn't exact) and that in general any part is a multiple of a certain amount of time:
In the first example every part has a length of ~x*10s. In the Queen-Song there comes a new part every 30s(I rounded quite a bit there with connection passages), in "Love is all around" we have the same game with 18s as the base and in "Magia" it's 16s for A and B and if I would cut the hold note at the end of C accordingly it would fit for that too.
I think it is advisable to identify that smallest timeframe for a theme and use it as orientation for switching pace/rhythm when mapping parts that are longer.


Breaks:
Now we remember the rules of thumb for breaks:
5-15s
Somewhat evenly spaced

Assuming that we want our beatmap to represent the song as well as possible I think it is safe to say that we want to map each distinctive part at least once.
Therefore we have to look for the parts we have multiple times.

Speaking about "Don't Stop Me Now":
Only A and B get repeated and only once. The second B is pretty much at the end and I don't think that it feels good if the introduction of the main theme the song is named after is skipped.
=> Include the break during the second A is the most sensible option(88-96s would seem reasonable)
Depending on how good you can map them it's also an option to use connecting passages as short breaks but for this piece i really like them and wouldn't skip.


Emphasis between parts:
Outside from changing the hitsoundkit(like Soft->Drum or something) between two sections the only way to put emphasis on a certain part is to map around it accordingly.
Speaking with Ursula K. Le Guin(retranslated so it sounds bad):

When a word is spoken there has to be silence before and after.

This can be difficult and varies a lot between songs.

"Don't Stop Me Now" serves as a good example(once again):
When hearing through the song it is very easy to feel a difference between the intro/part C/outro and the parts A/B.
This difference is defined mostly over the number of instruments playing. During the intro/outro the drums/guitar are completely missing and in part C you lack the piano/guitar while A/B are fully instrumentalised.
In general you can already plan that the intro/C/outro won't be mapped as dense(I'll talk about that later) as A/B and you'll also not make crazy jump patterns in intro/C/outro compared to A/B/D.
This way the parts that sound more relaxing are more relaxing to play while the parts where the band goes all out are going all out. Kinda makes sense I think.

An extreme example of this technique is this beatmap: https://osu.ppy.sh/b/179050?m=0
The pace of the beatmap and the song go hand in hand which feels very good for me(even though it becomes harder to fc compared to other maps of that stardiff).
I think this is very important to watch out for when mapping a song that has varying intensity.
If you compare it to our most beloved pp-farm-maps like https://osu.ppy.sh/b/323875?m=0 you'll see that this feels kind of boring but there aren't such huge swings in intensity which is why it's okay(even though you could probably do it better).



Third: Scheming a single part of your song

Having a song broke up in parts you can also divide the work in parts which is very nice in terms of consistent progress.
While I think that you can never go wrong with doing the previous part I think this one isn't mandatory for people who think they have a sensitive approach to mapping. It won't hurt in any case :^)

The idea of this process is that you're making a rhythm sheet(I think you could find a better word but I can't) that you use when placing circles:
We can utilize such a rhythm sheet by using the basic concept of hitsounding, meaning that we are putting a hitsound at each note of the main voice of the song.
(god, this description is horrible, please fix it for me)

To do that the first thing is to identify the major voice of the song. In almost any song with a singer it's the singer's voice.
Next you have to identify if your song is 3/4 or 4/4. That should go by ear. Just ask yourself if it sounds similar to a waltz and if it doesn't it's probably 4/4. Unless your song is jazz then it might be whatever(like 5/4 for "Take Five").
Theoretically none needs a measure but it helps a ton with orientating and makes it easier to identify rhythms that are repeated.

Take your paper and draw a horizontal line on it. Then write numbers below the line for the each beat/offbeat of that tact and draw a vertical line after the last offbeat of a tact.
It will look like this:


Now we're coming to the highly interesting and slightly tiring part:
Write x on the line at the corresponding beat whenever the mainvoice has a new note. If the note is between a beat and a off-beat make a "+" between the numbers to indicate it more clearly.
You can either listen to the specific part repeatedly or if you know it by heart you can hum/whistle it at a slower tempo which makes it easier to grasp(and you also have your hands free to write down what you're hearing).
I did this for the intro of "Don't Stop Me Now" to give you an example how this looks when it's finished for a part:


Writing the lyrics below can help in terms of orientation later on, especially when considering held notes(i indicated those by drawing a faint line behind the word).
The * indicates that there seems to be a bpm-change that's not as easy to grasp(the piano sounded weird) so I decided to make that tact empty and start the next one with the next vocal so I would remember to look into that more closely when timing the map. The piano sheet at the back of the page is from a piano arrangement of ZUNs "UN Owen was her" I happened to print out twice on accident.

You can do this for each part of the song(depending on how good you are this will take only a few hours) and when you did it you made a lot of progress:

1. you know the song a lot better from listening to the rhythm closely instead of just enjoying it
2. you have it all on paper so mapping will be a breeze as you won't even have to listen to the song again for half of the circles you're placing and the scheme works equally for every difficulty you're making
3. your technical understanding of music probably improved; future maps won't cause as much trouble anymore

(if you have an actual sheet of the piece you can skip this but I'd still recommend to do this once in a beatmapper's lifetime as your perception will change from doing so – listening is your most important quality as a beatmapper)

You can even go a step further and leave some space between each line and draw out how you could map this on the timeline for the different difficulties(make a dot for circles and a swung line for sliders and something different for spinners). There are always different possibilities and it's worthwile to take a look.

Examples: Referring to the sheet above it's obvious that we could make a slider from "world" to "I'll"(second line starting in tact 3) with low slidervelocity. Or that the notes for "ecstasy" and "don't stop me" should be circles to take the staccato into account.
Now that I'm mentioning slidervelocity: Cutting your song into parts obviously also gives you an overview of when to switch slidervelocity.



Fourth: Filling Notes

The intro part isn't supposed to have emphasis(see part 2) which is why it makes sense to focus on the vocals superhard and not map any additional notes.
Putting emphasis on part A with higher circle density is the most common way to reflect the increased intensity. The major question is: How can we do that without looking like an idiot?

Obviously we can't make circles when there's no sound which is why we should still focus on the different voices of the music to decide where to put our filling stuff.

In general our background consists of percussion and chords.
In my opinion chords aren't suited to be mapped as their purpose is to provide direct support to the mainvoice and therefore they're aligned with it like 95% of the time. As the player hears the main voice over chords whenever played at the same time there's nothing to get out of this.
There is no exception to that but chord-instruments can also develop an own melody for example during a held note of the main voice or in connecting passages(and obviously when it becomes the mainvoice in a solo/interlude). In "Goodbye My Lover" the piano has an own distinctive line during A which is why mapping it as the main voice would be an option for a repition of A but intertwining voice+piano doesn't quite work out.

In "Don't Stop Me Now" we can map to an instrument's melody at the Connection from A to B if we want to. Outside of connections and part D there aren't real opportunities to follow the instruments. They're too much in the background and it wouldn't feel natural to follow them.

All that's left is the percussion as a voice that goes almost completely independent from the main voice. It's of utmost importance to notice that the percussion is never random. Never.
Outside from drumsoli it's always consistent for at least 1x(and more often 2x) the timeframe we found in part 2.
It is important to make your beatmap reflect this properly by not including random extra notes.
You can actually repeat the process of making a rhythm sheet for the drums but you'll find that it's a lot easier due to the consistence of drums.
In "Don't Stop Me Now" it's fairly simple:

x X xxX

1+2+3+4+

for A and D(X is loud and accentuated, x isn't)

x Y x Y

1+2+3+4+

for B(Y is higher pitched compared to X)

xxXxxxXx

1+2+3+4+

for C(same as A/D, but it doesn't really matter as we don't want to map C dense due to chords missing)

I'm sure there are proper terms for the sounds the drums are making(xXY) but I don't know them so I just described what I heard. Feel free to tell me how they're called so I can include it.

Now we know the drumlines and the melody for the parts. It's fairly easy now:
Make sure there is a hitsound on every accentuated part of the drumline(capitalised letters) and see what it does to your map in terms of difficulty/enjoyment if you put in the lower cases as well.
Obviously you still have to value the main voice over the drums:
If the main voice shouts for a slider from 1 to 3 then you have to ignore the accentuated off-beat on 2 and make that slider. Sometimes the main voice will shout for notes on 1 and 3 but it doesn't sound quite like a slider. Experiment what 2 does when putting it inbetween, it might still disturb the melody so you have to decide when the drum's pace is more important than the integrity of the melody and vice versa.

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There are other ways to put in filling notes while making sense. These are always a consequence of the characteristic of the piece you're mapping and more often than not it will be perfect if you don't put in any extra notes.
Generally speaking: I don't think you can go wrong with the methods of filling i blabbered about in the previous section. The following can be good or bad depending on your song.


Think of making an arrangement for piano or guitar of a popular song:
The distinctive parts are the bassline and the melody but an arrangement taking only these sounds rather empty. Musicians will include notes that are between the bass and melody in terms of frequence and fit the harmony and play them along in a low volume especially when the melody is stretched out and you got no drums. Note that these extra notes have to be as boring as possible in terms of rhythm so you have to choose a continuous pace(like consistently spaced 1/2 in a line/light curve).
With beatmaps this is somewhat dangerous but it can work out fine for some songs. If you map this kind of filling notes as a jump pattern you are an idiot though.


Sometimes musicians will drop a certain note/percussion that is to be expected to make the song more interesting. It can be reasonable to put a circle into that place of silence(adjust the hitsound accordingly).


Sometimes connecting passages will be boring(which is either a bad job by the musician or intended). Composing an own drumline to lead to the new part can be an option but it has to be easily readable and not too complicated. It's best if it picks up the drumline from the previous part and transforms.

I'm sure there more but these are the ones that came to my mind when writing.

Fifth: Miscellanous

These are random (technical) things I thought about. They're sort of common sense but once in a while I stumble upon a map where it's done differently and curse it. You can't prepare them but you can prepare for not making these mistakes by knowing them beforehand.

About Triples: Triples are mainly used as a mean of melody(like in River flows in you) or emphasis for a single note. If you're using it for emphasis you have to keep in mind that a triple resembles an arpeggio meaning that the actual note always has to be the last in the stack.


Avoid streams at the very beginning of your beatmap(~10s). Unless your intro is long and cleanly connected to the actual start of the beatmap and has the same bpm it's nigh impossible to do a proper stream cause the player didn't figure out the beatmap's exact tempo yet.



I came up with the following things due to some bad experience I made as a beginner. I've seen people disagreeing with these which is why I'm marking them as such. They cater to easy/normal/advanced difficulties.

Overly dominant hitsounds can ruin the playing experience a lot - especially for unexperienced players. If you have no clue about hitsounding use the soft hitsound set and/or adjust your volume accordingly.
Look at these maps for example: https://osu.ppy.sh/b/7717 https://osu.ppy.sh/s/5381
While the hitsounds itself are okay or even pretty good if the beatmap is played properly(high accuracy performance) they are awful for newer players who have bad accuracy skills as the rather loud and dominant hitsounds will not only give very clear feedback when hitting off-time but also ruin the experience of listening to the song.
When I played the two maps mentioned above as a new player I had the immediate urge to stop playing as it was very unpleasant for my ears doing 90% performances and I even ended up deleting them cause I hated them so much(even though I loved the songs) just to redownload them when I got better. I still avoid the Rickroll-map because it is misstimed though.


Be careful with short repeatsliders that repeat multiple times. You might not be able to remember but there was a time when you tried to properly follow the sliderball on 1/2 or 1/4 with low SV and got your cursor into weird spots that way. Now you've become smarter and just hold down and snap to the next note but depending on your AR it can be very hard for the player to figure out on which side the slider will end. If your AR doesn't give the player enough time to get this information and react to it(and you better assume a slow reaction) try to make the next circle very accessible like placing it next to the body instead of letting it align with the sliders overall direction as the player may be on the exact different of the slider as the sliderball if the slider is short/the repeat fast enough.