I've been meaning to put up this link for a while and kept forgetting. So here it is:
If it has to do with drawing, you'll probably find a tutorial here. There are tons of downloadable lessons, broken down into Beginner, Intermediate, and Advanced. I could happily spend hours there (so I try to avoid going, lol).
When you open a lesson, you are given a brief overview. This is not the whole lesson. Click on the Download PDF to see more. Despite the fact that it says download, it does not automatically download the file, so you won't get something you don't want. If you do want to a copy, do a File, Save As from your browser menu bar.
Have fun, but keep an eye on the clock. Time flies when you are having fun!