Highlighting/shading on clothing+ Color suggestions for celt?

I decided to try out a 54mm figure......I picked out this Celtic warrior:

So on to the questions.

1.  For getting the highliting/shading in clothing folds, what order would you do it, or even better, does anyone have a good step by step for it?

I'm thinking, I could lay down my base color to start, then with a thinned and slightly darker version of my base color, get into all the creases, and finally a light drybrushing/highliting with a lightened shade of the base color?  I'm using GW acrylics. 

2.  How do you replicate patterns such as plaid, stripes and checkers on clothing?  Do you just try your best or is there a technique to getting really straight lines?  It would be easy on a flat surface, but going in and out of the folds in the clothing seems like it would be hard to get the patterns right.