Tutorial - Curves on Girls by *Ai-Bee on deviantART. Reaaaal good tut on different body types. In her deviant there is also a lot of links to others tutorials for men and women body types. If you draw characters, go see this.
Anatomy basic shapes - most people know of these simple drawing rules. But when you are having fun drawing you somehow ignore them, or maybe thats just me? Anyways, i beleive using them more consistently would improve my drawings a lot!