Gloss white is one of the hardest colors to paint. To get a good closs white finish it is more important working on the finish than getting the right gloss white paint. Using flat white and then polishing it and overcoating with clear gloss will give you a excellent gloss white finish.
If you want to just use gloss white paint then here is my procedure. Prime it first. Then paint a layer of really thin gloss white. Let dry making sure you cover it so dust don't get on it. After it is dry, use real fine web and dry sandpaper to smooth out imperfection. repeat step again until you have a good coverage. (maybe 3 layers will do). After you have done this then for the last layer spray a final layer of gloss white that is not so heavily thinned. This will be your final goat. You can polish this for a nice shine. I use lacquer thinner to speed up drying so you can get several layers done in one day.