If you paint it yourself you want to use a Urethane based paint, have a paint shop mix it and then use a 2 stage clear coat like Spraymax 2K clear. Base coat/clear coat is a good system to use. The base coat will go on pretty matte but the clearcoat will make it glossy. If you go with a enamel or acrylic and single stage clear it won't last that long in the sun and chemicals like gasoline/gas fumes can/will ruin it.

You should not have to do too much prep with a new part, scuff it up and wipe it down with a clean rag/alcohol. You will likely have to do some wetsanding and polishing to get it looking good, get orange peel and drips out. I would practice on a spare part before you paint to get your technique down.