I probably should have given this tip first. It's the piece of writing advice I give most, and even though it's short, it may be the most important thing I teach. Ready?
Give yourself permission to make mistakes.
This can be taken a lot of ways, depending on how you look at it, but the simplest is that you do your best work when you are trying things you aren't sure you can do. If you only write within your comfort zone, you will never do your best work. Taking a risk means you might fail. But it also means you might accomplish more than you ever thought you could.
So give yourself permission to make mistakes. Because you are also giving yourself permission to discover new abilities. Give yourself permission to write garbage and you give yourself permission to write better than you thought you were capable of. Give yourself permission to fail. In that moment, you are giving yourself permission to soar.