Select an up-close image of something bright and colorful (think fruit, candy, flowers) We want big shapes, not a bunch of tiny details.
Crop it to 8"x8". You can play with the color saturation/brightness/contrast a little to make it pop more, if needed.
Then you will put down a wash coat.
Then you will paint the contour lines using a slightly darker or lighter color.
Then paint background to foreground. I recommend looking at the painting page for more information on painting.
How to apply a washcoat: https://youtu.be/DtBTd5e2zzY
How to paint contour lines: https://youtu.be/5RQ-_6IHloM