You're going to make some mistakes early on in your music career. Fortunately, the internet is full of excellent resources with tips & tricks from people that have made mistakes and they're happy to share them so you won't repeat them.
Here's an article from the CDBaby! blog, "DIY MUSICIAN", by Dave Ruch titled “7 things I wish I knew when I became a full-time musician”.
Great advice for the aspiring working musician.