Its all about the consistency of the paint. There is no way to explain it you just get a feel for it. Every paint is a bit thicker or thinner so there is no exact formula to it. You need to thin the paint so that you get enough coverage without it being thick. A properly thinned paint will dry quickly but be a bit spotty (not spotted just not full coverage in one coat). It should take 2-3 layers to build up a nice base coat. If you do this each layer adds to the next rather than one thick coat drying unevenly anyway. After a base coat you mix in a high lite color and apply another thin coat only to the areas were light would hit them the most.
Here are the basics of HL (high light) colors.
red…add yellow (not white or you'll get pink!)
blue… add white
If you mix yellow and black you get olive green red and green give you brown and so on. A color wheel makes this much easier.
I work from a 6x6" inexpensive ceramic tile with glazing (white). This is very easy to clean once dry with a window scraper blade. I also use a bottle dropper with some flow improver (you can start with just a tiny amount of dish soap). Even though I have several 'high' end paints I still mostly use craft paints from Folk Art. Some colors are better when you get the high end paint.
Wash your brush often, dont store it in the cleaning water, dont let paint get dried up in the ferrule and dont drink you paint cup water!!!