Color Sketches

I've been trying something new lately, painting 30 minute digital paintings from random photos, just trying to capture the overall light effect and color as quickly as possible. I don't know a lot of the tricks to speedpainting, so I'm just using a round or a square brush for everything. Here are a few of them:

They're nothing much to look at; more of a learning tool. I'm hoping these will help me in getting more accurate light effects when I'm trying to paint from my imagination later.