As an artist you should not put yourself limits. Don´t stop learning new things. Different ways to color is one of those things. Don´t limit yourself to simple flat color and flat shading.
There are so many possibilites of coloring. Be confident and brave enough to test new things and experiement with what you already can and know.

Art has no limits and so don´t you´re skills.

1. Simple Flat Color in thin Lines AND thick Lines

Other kind of Linearts

Colored Lines

Abstract Lines

2. Simple Shadings and Lightings

a) Hard Shading with hard Lighting
(You might call it Cell Shading) 
..and fading Hard Shades: b) Soft Shading and Lighting

c) Shade Combination of a) and b)
d) Soft Shaded Hard-Shades 
 e) Double Shades Soft and Hard
f) Triple Shades Soft and Hard 
d) Smudge Shaded 

3) Abstract Shading and Highlights

Highlights instead of Shades

Abstract Highlights


5) LINELESS
 

6) Watercolor-ish and similars