Hey Kevin. First give it a bath to remove any oils or impurities from handling, etc. Let it dry and then spray it with a plastic compatible primer.
I would use gray primer for almost all colors except rust. For that, I would use a red primer. This will give the plastic some "tooth" for the top / color coat to adhere to.
Acrylics will work fine. I prefer the cheap big box store paints myself. There are a lot of camouflage colors out there that look good. I like the olive green color and then I spritz it with a wash of India ink and alcohol. On my new layout I used a combination of "metalized" silver with a little flat black overspray.
Good luck and post some pictures!
Donald