I'm using Tamiya acrylics.
If you're doing a repaint/touch up, I tend to paint everything a particular colour.
I let that coat dry. (Takes an hour roughly with Tamiya paint)
Then I apply a second coat (To start adding detail.)
Theeeeeeen I apply a third coat (which is anything from a detailed coat to whatever.)
Sometimes a fourth coat is needed when I mess with the skin, because it's just a huge experiment to make sure you get everything.
Basic techniques I use are: Using a dry brush with barely any paint (dark or light paint) to detail armor and skin.
For this, I have Tamiya XF-1 (black) and I have Tamiya X-11 Chrome silver. I apply the black first, then a little bit of silver.
You'll see in my upcoming pics of my Predator. (Been lookin for my iphone cable everywhere!)
That I use this technique for a lot of things. Very simple and you'll master it quickly.