For paints, I use Model Master Acryls by Testors. But if I am in a pinch, I will use the regular Testors Acryl paints that you can get at Wal-Mart. The only time I prime a figure is if they have a detail that I don't want showing through the paint, like Spider-Man's webs. I use the cheap model painting brushes that they sell at Wal-Mart that are about 1/2" long. They lay nice and flat, which is very useful.
After I have painted a figure, I use Testors Dull Coat on top of it to seal it. After painting and sealing the figure, I start on the detail work with an ultra-fine black sharpie. This is when I do the face. I draw the features first with the sharpie, and after that dries, I add colors in by dipping a toothpick in the paint and applying it lightly. This is also how I do thin colored lines on the body of figures like Quicksilver's lightning bolt across his chest. You don't need to seal this paint, because it doesn't get any wear like the joints do.