I use Matrix Volumizing Shampoo (Color XL, for colored hair although I didn't really notice it doing anything for my color, but it volumizes well)..
TIGI - Queen for a day.. It's a volumizing liquid spray, you spray it all over and blow-dry, loads of volume..
After I'm done blow-drying my hair i used either the Matrix root lifter, or the cheaper Aussie Spray-gel, and using a round brush lift my hair up and blow-dry again...
Oh yeah and finish off with TIGI Hard Head Hairspray all over.... (never buy TIGI Catwalk though, their pumps tend to be defective)
Also if I'm going out I'll tease the hair and spray it with hairspray... This gives over-the-top big hair...