1. colour theory things like how colours can look different in a different lighting and shading,saturation(how bold the colour is) value(how dark it is) Complementary colours (contrasting colours that go good together) and analagous colours (colours that are close to eachother on the colour wheel *red orange yellow*) 2.anatomy I've gotten considerably better with my traditional art.however i am yet to see improvement in my digital art. 3.backgrounds I'm trying my best to draw them,and i think it's going pretty well! 4.composition. I'm still trying to figure out how to make art that tells a story,but i think i'm getting there.