To try your hand at this, you could go to Home Depot or similar stores and get spray paint or paint samples. You just have to remember to sand the surface a bit before you paint, so that the paint sticks.
Whether or not you feel like you are good at painting, you can adjust the designs to your skill set. And really, painting is just breaking down shapes into simpler shapes. And you can always use stencils if you don't trust yourself to freehand it.
In my experience of painting, you can't go wrong if you use colors you like and claim to have intended any/all mistakes.