Make sure you pick up the

+

and

+

combos when you can (in the fist skill tree), they will let you break apart certain ceilings/floors. Somehow missed that the down version of that and skipped a bunch of breakable floors I thought I would unlock a skill for later, and had to go back to them after I realized my error.
Also, if you come to doors guarded by blue lasers, you can open them with the whip. It's not mentioned anywhere in the game and easier missable until you Google "how do I get through the laser door here?"
