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.
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.