Trust me, you don’t. Everybody progresses at the game at their own rate, and everyone’s at a different point in their journey. I’m working on beating The Nightmare as my 2nd demon. Some tips I’ve learned are:
-Copying the level can really be useful. Set start positions at low percents and try to beat the level from there, or use it to get past parts your struggling with.
-Beat the level in Practice 3 times at the very least, so that you know each and every part and won’t be thrown off guard by anything.
-Beat the official robtop levels, or at least practice them, although they are on the easy side, they will help you get better. Some good ones are Jumper for memory and getting used to upside-down ship, Clutterfunk as an all-around good challenge, Time Machine to practice good timing, Hexagon Force for any duel parts, Electrodynamix and Clubstep for memorization and timing.