I've been out of model-painting action for a while - blame Halo 3 and Xbox Live. Can anyone point me to a tutorial that covers this? Something fairly professional, not just brushing bestial brown onto the bottom. I paint to a hight quality (certainly nothing near Golden Demon) and though I don't normally do this for 40K stuff, it just seems to suit LOTR models. I saw a good tutorial once layering on different colors of brown to look like clay and mud. Here's my mini so far:

Thanks for your time.