http://howtodrawmanga.com has a few good free tutorials...
when I'm trying to learn how to draw anything, I got through a process:
1. Grab a picture of a character, and look at it, and try to draw it. When you're satisfied, put the original picture away.
2. Try to re-draw what you just did, using the drawing you've already drawn.
3. Repeat this until you can draw it without looking at it.