I've never been too confidant at colouring. Below are two versions of the same panel from one of my upcoming stories. In the first version you can see my attempts at colouring and in the second you can see me being totally outclassed by Fin Cramb (email@example.com) who coloured the rest of the strip.
I always find this kind of thing interesting so I thought I'd share it. I will get around to posting more of the story some point soon.
Fin Cramb's version (note the attention to light sources)