Use the Rig Stars add-on to add more realistic deformation to your rigged meshes.
The Blender RigStars Add On allows you to quickly and efficiently expand your rigs and armatures and bring rigging to a complete new level. This add-on is designed for holding volume in critical deform areas of your mesh and correcting shapes of it either with shape keys or just normal weight painting.
Rig Stars sells for $14.95 on the Blender Market
