learning how to use colour
(all my own work line work/ screen tone/colour)

first of all, is that your line work? Do they belong to an other artist? If so, do they know about it? Other then that, nice coloring. I'd say add more tone and shadows for depth if you want to take a step away from the cartoon look.

Base +6, hZi +10

You're really good that awesome, Good Continuation!

Base +7