Five Pencil Method
Awhile back, I came across a site run by an artist named Darrel Tank. He's an immensely talented artist and this site of his, FivePencilMethod.com, has tutorials from him on his techniques. I'm using it to sharpen my skills, and there are some very interesting things on there. One thing that I found especially interesting, and helpful, was the technique for drawing hair. If you're a beginning artist, or if you're like me and you want to sharpen your skills, I recommend that you check out Darrel Tank's site, FivePencilMethod.com.