>>54166372Making first moves into uncharted territory usually involves looking at tutorials, other people's studies, references, etc. It's the same for most skills, imagine learning programming through experimentation only.
Things don't stay that way though, as when you have a basic understanding of what you're doing, you can experiment again, test the boundaries of your skills, and look up another tutorial when you hit another wall.
I'm still not sure what you mean by theory, in art it's mostly just names for techs and tricks that you use to make stuff look better, it's not like you're studying for a test. Give some examples of what you're falling short at, things that look bad in your images, I'm curious.
