I have a wavy bob, so volume is my best friend. :-)
I have had really good luck with Beyond Zone Noodle Head Curling Mousse.
I put about 2-3 handfuls schrunched into wet hair. Then I add a bit of LALSG for increased hold. Then I pixie diffuse upside down. I get good volume this way, oh, and when I got more layers added, that helped a TON.