First rule of thumb is that it will look like crappy if its flakeing off. Sand the panels and make sure everything is super clean. Use adhesion promoter. Don't cut any corners on prep. Paint doesn't want to stick to these panels, so you must force it.
Other than that. Are you spray painting or using automotive paint?
You can use HOK and have it look like $2 discount spray paint. Everything is in the prep!!!! Automotive paint will look better and last alot longer! Uv additives gas resistant and harder! Now if want auto paint but don't have the equipment. Check out Alsa killer cans or if go to home depot for ge name of it, but it's a spray system aersol can on top and a glass jar on bottom which you put your paint in. Then have your own spray paint