Play with blend modes in photoshop. www.photoshopessentials....

That's what I do... but I don't know how realistic makeup I make...

Hm, I have CS3, my blend modes looks different ^^ But I tried that and it wasn't good

Make the makeup on separate layer... color only and then use the blend modes. CS3 blend modes shouldn't be that different.

Oh and google for something like makeup in photoshop, you should find some tutorials.