Aquarell pencils used on the copied inital lineart.

Lessons learned so far:
a) I need a better system to differentiate objects in the fore from objects i nthe background when they're of closely related colors.
b) I need to better understand how the brush and water affect the colors as wel las the paper.
c) I need to work out a system to produce structured surface like gravel and polished vs structured surfaces.

Recommendations of tutorials and online ressources warmly welcome!