Here's a piece from Life Drawing classes in dry pastel. I really enjoy using pastels : it is like painting with a dry medium, a cross between drawing and painting. Rather than building up colours in overlaid successive layers, you have to be bold and lay down strong colour blending with other colours on the paper a little as you go. Once the paper becomes clogged, as it does rather quickly, you can't add any more colour on top.

I prefer to use a limited number of colours such as burnt and raw sienna, and a couple of blues - a complementary of the warmer colours and a light one for reflected highlights - but there's no rule as to the number of colours you use.