We've finally slipped out the technical realm and made it back into the art world. Feel free to call your parents and tell them you wont be speaking to them anymore, heh. Coloring, like drawing is personal preference so I will not go into the details but I'll briefly outline my system here.
*Those black bits are because of .gif compression. They probably wont show up in the final version.
When coloring for Halo Babies I use a system of base, shadow, and highlight colors for most objects. Matte objects like the Chief's underarmor doesnt have a shadow or highlight color so there are exceptions to the rule, but this is a common way to color and get a 3D effect. If you want to go uber-3D add a reflected light color to really make your images pop, but for the purpose of speed I don't use it. There are also special cases like Cortana's details and the Chief's mask that I won't go into but if you know what layer masks are do, then you might get the gist. Onward to the comic!