After the linework is done, adding base colors is needed.
Base colors will help me greatly on how I can paint, since each color can be locked and painted on without spilling to other designated area. Also I can change the color later with color tools without putting too much time. The only problem is I need to use lots of layers and fill everything in my work myself. Sometime the magic selecting tool can not reach a tiny bit area which I need to paint it by hand later.
The next step is I need to adding shade and highlight. Probably the second hardest part of all my work.