Hey lex! So it generally works out nice! Most of what I altered are things dealing with Viscom 2 (like on the helmet), material indication (on the fur thingy and the clothes), and on the background color.
1: I changed the background color because it was really saturated next to your character. Dulling it down is more appealing to the eye and moves focus to the character!
2: I pretty much just applied viscom 2 to the helmet, along with refining the design of the mask part (so that I could light it better). When painting more complex shapes, it's important to know how they act in light- just something to think about!
3: Watch out for the burn tool, it isn't a great way to add shadows. It's more effective to paint them in, and in some cases, using overlay layers can help! Just refine that painting skill over summer- do master studies, paint from life (try painting your computer desk from where you are!) or painting outside, or even doing photo studies helps.
4: His stick was a bit too powerfully orange, so I dulled it down to a less saturated brown.
This piece has alot of potential! try developing this character in sketch form too, could turn out really cool! do design studies of the helmet (annis has some from dp2 on his blog). Maybe design other members of this group/clan/squadron!