Topology!

Here's a few links for references on good topology!
Limbs:(hands legs etc.)
http://wiki.polycount.com/LimbTopology

Body:
http://wiki.polycount.com/BodyTopology

Face:
http://wiki.polycount.com/FaceTopology

Shoulder:
http://wiki.polycount.com/ShoulderTopology



General(principles etc.)
http://wiki.polycount.com/CategoryTopology