as someone said if your going to use acrylic paints do yourself a favour and get them from an art store like Michales or Deseers etc.
they cover better, usually with only one coat, they dry much faster, they don't smell near as bad as the cheap paints and they don't lose the color when you apply a coat of poly even when the cheap paint is seemingly dry.
I get mine from Michael's and I buy the large bottles of the colors I use most, they are 12.99 and I always get a 40 or 50 % coupon so really they are well worth it.
Paint from walmart and dollar stores are just not worth the trouble IMO.
I do think I am going to try spray paint like Crupiea says he uses...