Just like anything else, you get what you put into it. I painted my plastic the first time and it looked ok. i ended up wet sanding it and painting it again because the white showed every little bump or imperfection that was in it. After the wet sand with 600 and wiped it down with rubbing alcohol. it turned out pretty good. I let the plastic pieces sit in the spare bedroom for about a week before i put it on. The hunter green I used on the tank pieces turned out really well. Use slow even coats or it comes out looking like shit. The over spray is a killer with that stuff.
thats my .02