Even when my contributions suck people think of it as a positive and often teach me the right to do the code or explain why the change is not necessary.
As far as books go I don't have anything to recommend. For me improving fundamentals was really about figuring out what I didn't understand and diving in to learn it. I prefer online materials over books but one book I have read that I thought was great is 'the pragmattic programmer'. https://www.amazon.com/Pragmatic-Programmer-Journeyman-Maste...