Make small animations, take the character and background of your choice, then color it using any color medium (oil, pencil, water color).

Some examples you can try:
1) A bouncing ball
2) Bird flying in the sky
3) Plane flying
4) Sun with bright sun light

Make sure you are coloring both background and character by handwork and no computer involved until its coloring and editing on a software.

You can share your work with us to get feedback and other references.