I've created this list of notes to myself to keep track of things that I've learned the hard way. Fortunately all of them weren't learned the really hard way, but rather were sudden realizations that I had about a better way to do something.
If you get the feeling that something is going to go wrong STOP right there. People's intuition about these things is actually pretty good. If you STOP and listen to yourself you can avoid some bad injuries. Even if you aren't certain why something is wrong, stop and think about another way to do what you are doing.