I'd change the first stage. Make him wear only shorts.
Second: tshirt from first stage+long pants+small one element wings (like... only their upper part)
Third: long sleeve shirt+bigger, 2 element wings(way they are now)+headband and shoes + something more(?)
Fourth: big wings+jacket (3rd stage one)+face change+something more(?)
Fifth: keeping most way it is now + new elements(?)
There are some things you could improve. His hair and pants could use some changes. Starting from simple hair and changing in next stages, same goes with pants, they could use more variety, you can also play more with colors, like skin getting darker in later (starting from 3rd or 4th) stages.
I'm not sure about those sparkle things. I think they go against clear-cut rule?
Aah, I never thought about only putting one wing...I forgot about that. XD
The reason why I gave him a shirt and wings at the first stage was because of two reasons: 1, I don't know how to draw him without a shirt, and 2, I was thinking that the wings will stir people to buying it. First impressions are always important, right? Ah, well, I'll go through your suggestions with the ones my little sister suggested and see what I come up with. XD
Thanks for the help!