Honestly, the best advice I've ever received is something I've heard constantly throughout my lifetime. I think most people have heard it before and most people will follow it. I personally struggle with it from time to time because I not only don't trust myself but I find it difficult to trust others. So the best piece of advice given to me is to trust your gut. Building trust in myself is something I needed to do and trusting my gut comes with that. Turns out your first feeling is usually right (and at this point,  it's how I get through guessing on tests) so I trust myself a little more now. Like I mentioned, testing is a little more bearable. I stopped second-guessing myself so I do better in school. Social situations are easier to handle now considering I'm relatively shy. I trust myself around others because reading people is easier when you trust your gut. Thus, trust your gut. It works.