I think if your goal is to make the arm rest on the hip, it should be higher up. That low, the surface is basically vertical so the arm wouldn't be comfortable there. It's also unclear whether she's got her hand in a fist with fingers against the hip, in which case the entire arm should probably be positioned differently, or if her palm is on the hip and you've just neglected to draw her fingers, in which case the arm position is fine. Try making this pose yourself, that should help you figure out how it works.
As for the palette, define "bad"? It doesn't really matter where you get your colours for the end result, what matters is that you use them effectively. To that end, understanding why your colours work or don't work is important, and that understanding can develop in many different ways. Some people learn by experimenting, some learn by analysing others' work, some need to have things explained to them, some have other methods still, and most people like a mix of methods. The key thing for learning is that you think critically about your colours, don't just accept something because it looks nice.