
Soft bodies are well suited for:
– Jiggle on moving characters.
– Elastic and deformable objects made of materials like rubber or gelatin.
– Tree branches moving in the wind, swinging ropes, and the like.
– Flags, wide sleeves, cushions or other simple fabric reacting to forces.
– Soft bodies work especially well if the objects have an even vertex distribution. You need enough vertices for good collisions. You change the deformation (the stiffness) if you add more vertices in a certain region.
– To speed up the collision calculation it is often useful to collide with an additional, simpler, invisible, somewhat larger object.
– If you try to cover a body mesh with a tight piece of cloth and animate solely with soft body, you will have no success. Self-collision of soft body hair may be activated, but that is a path that you have to wander alone. We will deal with Collisions in detail later.
– Try and use a Lattice or a Curve Guide soft body instead of the object itself. This may be magnitudes faster.
Source: Blender Manual