I wish when I was younger someone had said to me:

Everyone’s advice is based on their own interpretations of their successes and failures, which are produced by luck and chance just as much as methods and intentions. Take advice about how to do X with a grain of salt when it’s coming from someone who has only done X once and is still riding the wave of that success. They think they know how they did it, but they probably don’t. On the other hand if someone does X constantly, listen to everything they say, figure out why it’s true, and imitate or adapt it.