Shading advice

[Emera]

I've been playing around with graphics lately, recolouring images and adding to some, but I'd like to take it to the next level. I'm interested in getting to a stage where I'm comfortable with creating simple graphics that look good. Obviously, there has to be some sort of starting point. I've managed to create a decent looking (in my opinion) hat shape using the hat template provided in one of Bell's threads. I'm happy with it so far, and was playing around with adding shading. I'm pretty hopeless with it haha. Does anybody have any advice to give me about how I should go about adding shading to this image?