Comic Cover WIP

I like the official comics and given they have like, a million goddamn covers, I decided to try making one too! I'm coloring it currently, but it's taking forever. If anyone has any tips or guides for coloring stuff at night, or just coloring in general, I'd appreciate it. Color theory escapes me. I know I say I'm going to finish all of my stuff and never do, but this time I mean it! I'll at least shade it and replace this one if colors don't work out.