Basically if you want them looking really nice, you should do them just like an automotive paint job. Strip the paint, sand down any imperfections (I have actually heard of people using small amounts of bondo in deep scratches), make sure all surfaces are scuffed up good with some fine sandpaper, primer, sand again, paint in multiple coats, put a clear coat or 2 on them (Duplicolor makes clear as well), and then wetsand and polish at the end.