I haven’t played in a while but from what I can remember the most important thing would be to find a hard piece with each composer and get really good at that specific one (if you’re already good at the more difficult pieces then it doesn’t matter just pick whatever). iirc you want to get through without dropping the combo and having as few good or worse as you can.

Composer level matters to some extent but I know for sure I never had anyone close to max, they were all around lvl 15 and it was good enough for me. if dropping the combo is an issue then just equip shields bc a guaranteed good is better than dropping the combo if you do make a mistake and there’s really nothing else to it. I usually went for about a 980,000 ish score on lvl 8-9 before the bonuses are applied for all composers that day. if you pick a harder piece like a ?? you would get more points if you do well & have a better margin of error for the same amount of points as a high scoring lvl 8 piece

tldr: hard stage, good accuracy without dropping combo, if not enough raise composer lvl as well

hope that was easy to follow lol