If you can organize yourself in watercolors like this...the layering process...then you can certainly do it in Photoshop! Because the coloring process is exactly like that. By floating your drawing on the top layer, and adding colors in the order you want them (and making sure you label each layer as you go for ease in remembering each one) you're home free. Truly!
I can link you to some tutorials on how people color in Photoshop if you are curious.
And if you used your own hair as the model...you have very gorgeous hair. ;)