yeah sure red line set-up is important but its not devastating. you can search up bpms, rip off the timing of other maps without outlash (also considering you're probably inspired in mapping some other song because you saw a good map of it and love the song too) or ask in the timing request subsubforum (if anybody uses that, idk tho never used it before).
this suggestion, however, also deals with fundamentals.
i learned from tutorials and pishifat that "mapping expresses the song." therefore, as a new mapper, i recognized myself as a "concept" mapper, using themes for wide scale maps such as short sliders, all curving slider and flow, all tech, half of playfield slow and half of playfield fast. because of this, i prioritized "song expression" over "map creation." now, this isn't bad, per se. however, i found out that i would never get far with this mentality, and i slumped twice. additionally, my ideas were still ripe, and i could not deliver some concepts properly. (some were pushed though, i'm trying to rank it right now)
but lets be honest. is there ALWAYS meaning to that slider, or circle, or anchor, or whatever being in that exact position? i can use a different pattern and still say, "ah, yes. this fits."
the answer differs for everybody, however.
bottom line: don't be so bumped up in terms of concepts and "over-expression" of music.
this is NOT to be confused with not following the beats of the song. DO follow the beats of the song. however don't be so hung up on stuff like "ok since this is rock song i will use dirty red anchor sliders to express anger" or "ok here ill use cs7" things.
pishifat sums this idea of expression vs over-expression well, in his video "fun vs. good". can check it out to better get this next one.
by trying to map "fun" maps first, your aim is to develop your imagination in such a way that you can solve any roadblock in mapping. this is the fundamentals i'm talking about.
once you can do that, THEN you can define what is "good."
is it feeling? is it fun? is it concept?
also, another thing. say this is a set of notes on a song: | o | where o is very weak and | is strong. if you're at the point where you're comfortable to not map the o with some sliderend or something like that, then you're doing well. this is also what i mean by don't over-express. sometimes, letting the note extend for 1/1 whole beat gives more, slower expression.
imo now the best difficulty to start mapping is hard diff, but eh depends on you.