Shoegazer wrote:

Getting good accuracy is basically being able to find the area where you'll be able to land good judgements all the time and containing their hits into that small enough area for the game to register as the best judgements possible. For most players (particularly for top-tier play), the only good judgement is a rainbow 300. For you though, normal 300s also apply.

SPOILER

Finding that one area is not easy by any means, especially for maps that you can't full combo all the time. It's better to start with an easier map first, since the window should be at the same position - just different sizes because of the difference in Overall Difficulty. Avoid any maps with long notes because this will skew the timing error unnecessarily. Hit completely naturally, as if the judgements weren't there at all and you're just playing as if you found the area. There's no point in trying hopelessly to find that area for now. Check your performance graph and see what was your timing error.

If your timing error is something like:
-12.00ms - +25.00ms: Increase your HitPosition by increments of 2 and try again. Repeat until your timing error is about balanced, by 2-3ms difference.
-25.00ms - +12.00ms: Decrease your HitPosition by increments of 2 and try again. Same thing as above.
-18.00ms - +18.00ms: You're probably playing a map that's too hard to find the area accurately. Play something easier and more constant. If you can easily full combo the map you're playing, then I'm not quite sure how to help. Either that, or that is already your "area" and you'll just need to learn how to sustain those hits.

I would like to note that HitPosition is not a be-all end-all way of finding the area where you can land judgements on. For most cases, the area wouldn't be perfectly aligned with the HitPosition, because the HitPosition is limited (the number the HitPosition is based on is the height of the receptors in a 640x480 window of osu!mania). You can get close though, so try your best to find that position and modify accordingly. The gap between where that area should be and the area you're hitting comfortably in should be about 4-5ms at best.

That's the hard part for most people, the easier part is actually sustaining those hits. Sustaining hits is definitely more aural-based more than anything else, though there are many times where visual play is more predominant, like in charts with very unorthodox rhythms and are not constant at all (none in o!m comes to mind, but there are many SM converts like this like Quatre Mains). You don't really need to pay attention to the sync, you just need to be able to follow the tempo well enough to ensure that your hits will be registered as good judgements. That's where the practice makes perfect part comes in, familiarise yourself with tempos of certain speeds and you'll be able to do it easily. Unpredictable rhythms are hard to do and honestly I don't even know how to improve on those myself other than memorisation. I'll find out how to do them sooner or later.

Just two more things when it comes to timing that could help:
- If you naturally hit early (which is easy to do and I'd imagine hitting early is more common than not), after you find that area, decrease your HitPosition by 1. This should move you to the middle-late area, and it is easier to notice that you're not in that timing area both visually and aurally. People also tend to rush more easily as well, so it's better to compensate that by forcing yourself to hit slightly earlier than you should be.

- Increase your speedmod gradually. As players get better, they are able to process information faster. Increasing your speedmod will help players process information better because the spaces between notes visually are more noticeable and they also have a lower chance of rushing. In addition to that, it gives the illusion that the windows are larger than they really are, compared to a lower speedmod. This is because with a higher speedmod, the notes move at a higher speed (duh) and thus there is less time needed to travel from the bottom or top of the screen to the receptors. Thus, the percentage of the time the arrows are in your vision (i.e. distance between receptors and bottom of the screen) is higher, giving the illusion that timing is easier, despite the timing window being the same.

There's probably some others, but I probably forgot. Hope this helps to some extent.

Shoegazer wrote:

Alternatively if you want some short-term results, you can play HR for like an hour and play without HR for a while. Your mind would adapt to the tighter window temporarily.

Bobbias wrote:

If you have no sense of rhythm, IMO the better way to train that is to use hidden, not just increase your scroll speed. Since hidden forces you to be unable to see the judgement line, you are forced to learn to time by sound.

abraker wrote:

or trying to tap to the beat (which you might suck at).

31Gabe wrote:

Marvelous timing? Make sure your global offset is correct and the steps are to the beat. Make more precise steps in the game alone to get more Marvelous ratings.

In my osu!mania skins, Rainbow 300 is Marvelous.

Make sure your global offset is correct