Image is mine. Actually, one of my best tries at painting.

So how do I do it. Can you recommend some books or something? I tried looking for anything related to fundamentals of painting, but all I could find were books focused on specific subjects, like light, landscapes, humans...

But how do I paint, how do I mix the colors so they look decent. Everything in photoshop looks so damn clean, and when you try adding some color so that it doesn't look so clean, it looks hideous and you can still see the unrealistically clean parts.

I am not an absolute beginner, for two years I've watched numerous videos about painting, and as you can see none were useful, so I want to start for the beginning.

Help please