Here's an example of a cloak I did.
Here's how it was done:
The whole cloak was covered in color A, then a good wide chunk of the raised sections were covered in B, then the top most ridge in C. I don't remember the names off hand (I'll have a look later on) but all three are straight out of the pot GW colors.
A is easy, just cover everything. To get a nice straight line for the edge of B, start the brush where you want it and apply the line in a single motion, that way you get a straight line. Making one smooth line may result in it not going exactly where you planned, but it doesn't matter too much because the boundaries between the colors are pretty arbitrary. C is a lot like drybrushing, you're just applying a line right along the ridge so if you align your brush perpendicular to the ridge and drift down the brush will hit the ridge before anything else and leave a bright line down the middle.
I you can't find three colors that work well together you can make your own. I do it by taking the darkest color, 2 parts of the dark plus 1 part bleached bone, and 1 part dark plus 2 parts bleached bone. That's where the stripes on Erkenbrand came from...