My golden rule is never get too frustrated if trying to draw results in a few duds at first. Warm up doodles that are kinda crummy can be fun to do and will eventually lead to really getting cracking on an idea you've may have had in a while.

Another thing is even if something ain't perfect the first time, redraws can also be really fun. It allows you to see how you've grown with a direct comparison. Especially if you practiced something and now no longer have struggles with it.