[TonyRivers2]

Not half bad.. I like the basic shading but its a little flat adding a darker gray countor will help the back part look more round and adding lighter grey and lighter blue in small ammounts will help display the shines on the helmet (in the front) also a small ammount of white to the visor could do it some good. Hope this stuff helped I'll try to show you what I mean in a few...

Edit: fixed it up a bit I think a major problem you had was contrast (which I didn't fix all the way due to time constraints) It looks like you used basic MSpaint colors. For a better shade effect try to change it up adjusting for midtones. Also your black outline took away allot from the visor so its gone. In addition little changes were made to the outline which was otherwise decent. Maybe this can help you out a little with shading good luck and keep up the pratice - Tony