SAND SAND SAND, rough grit to light grit, take out all the deep scratches, then make the whole thing in a fine rough stage, enough to hold paint but not too scratchy that it shows through, and clean clean clean especially if you used "armorall" type polishes on your plastic. Prep is the most important part to painting anything (cars, bikes, quads ect.) If you do it right the paint will hold and not flake off. and you need a flexible paint.