always start with the basic body shapes you want. Not just like circles and triangles, but complex shapes. Also, it makes bodies a ton easier if you sketch the frame on 50% transparency. That way you can easily see all of the limbs and joints.
Draw a "skeleton first*. Basically a stick figure very lightly. And slowly add details to the skeleton. Once your happy with the basic shape of it, and any pose it is in. Draw around it.