You could also use either cloth or soft bodies, just create a vertex group to define the parts of the model you want to have the jiggle effect and bake the simulation. With this method you can have a very good looking secondary motion. Maybe not realtime (depending on your machine) but pretty good anyway
Thanks for the response @julperado !
That will be very helpful in some situations I’m currently working on. I didn’t realize I could weight paint the vertex group for cloth.