The pros don't use greasepaint, they use PAX paint.
PAX paint is a combo of acrylic paint and surgical adhesive. You paint the mask just to the edges, leaving 1/8 of an inch or so unpainted. After it is on, you apply more PAX paint to the edges and your skin to blend it in (it's okay, PAX paint is used on bare skin all the time, it is how they did Mystique in the X-men films).
You can buy PAX paint, especially the non-tacky kind, at fxwarehouse.com. If you use it, make sure you get a good remover like the Agent-X fxwarehouse sells.
If you can't order, use craft acrylic paint on the mask as suggested by Sychoclown, then blend it in to your skin with a coating of makeup on both mask and you.
For good makeup, get the Ben Nye color wheels (or solid colors, whatever you need) and setting powder, also from fxwarehouse.com, it is simply the best on the market.
I ain't no salesman, just an extremely satisfied customer will a lot of years playin' with this stuff.