Hey, 22-year old self, you know all that stuff you're worried to death about? All those failures and existential crap that's keeping you awake? It doesn't matter. I know it really seems like it does but, trust me, it doesn't. No, not that stuff either: It really doesn't matter.
Now stop reading about mistakes to avoid and start discovering new ones to make by yourself. Those mistakes will end up perversely leading you to your greatest successes, but you can't make them if you try following someone else's retrospective perfect blueprint for happiness.