Originally Posted by BlurredD

I find it helps to have the music picked out early on so I don't have extra trouble finding a good music match for the level later on. (...) If you start half a level and can't finish it, you can try stating a new level and get back to the other one some time in the future. You might even have to. (...) I often start with the background to help me judge how many layers I'll need with x and y speeds at 1 (this issue also may depend on the tileset). If the background turns out to be really good, it's sort of inspiration to get the rest of the level finished.