Okay, so to get started, you're going to gather the things you need:
. Various nail polishes &
. Your unwanted guitar picks

So, before you start to paint your pick, you should draw your rough design on a piece of paper, i just traced around my pick and drew on that :)

This is the pick I'm going to use
:D

So to start i used a white polish and painted a base coat. (I needed 2 layers to cover mine.)

Then, I used a red polish to paint the little heart...

Then, using a black polish i painted on the character and after that dried i coated it with a clear polish, let that dry and... you're done!!