Plasti-kote is a brand name, has nothing to do with painting plastic, lol.
The following has worked well for me, I am also NOT a painter but have gotten decent results with spray cans. There are probably other more professional methods, but this works on a budget.
If you want a halfway decent color match use the Plasti-kote Import Color spray cans. They can be found at Autozone and even some department stores (Walmart?). If you have a solid color (super red II, Super white etc) you can get away without clear coating after the base coat. If you have a pearl color you will want to clear coat afterwards.
Prep by wet sanding with 400 grit. Then use a filler primer to help even out the spots where your original paint is worn through to the plastic. Wet sand after primer with 600 wet. Wash with soap and water, dry COMPLETELY (let it sit in the sun for an hour or so), use a tack cloth to pick up and left over dust and get ready to shoot it.
Mask the area well, hit it with a tack cloth again afterwards. When spraying use a steady pace with long sweeping motions. Overlap your strokes and keep an eye as the color goes down, you are looking for even coverage. Dont try to get it on too thick all at once. Several lighter coats work better than one heavy coat.
Word of warning though. Buying sandpaper, masking tape, primer, paint etc adds up real fast. You might be suprised at how much you will spend on paint cans to get a good coat. In some cases its actually cheaper to pull the parts off you want painted, and take em to a shop and have them sprayed. Tell them you want them as cheap as possible and that you were going to otherwise just rattle can em, and they should be able to get it done for less than you might think.