I am (was trained as) a visual artist, and I really can't offer any constructive criticism. You're doing everything right. As someone who is self-taught that's incredible, and you've already sold a print!
What I like: the quasi folk art quality, standing midway between realism and representation (photo like work vs work that more suggests the subjects), your bold images, the colors you have chosen in relationship to each other; your compositions are very good. Keep at it!
Best ~ raedawn