Start out with clean hair and use a volume boosting shampoo.  Be careful to not let the towel sit on your hair too long as this will flatten your hair and volume will be harder to achieve.  Use root booster and work it in well.  Use a round brush and over-direct your hair as you point the nozzle of the blow dryer in the area that you are styling.  After each section of your hair is dried, brush your hair in the direction that you wear and you will see instant lift.  To finish off a perfect look and great volume, finish your look with a misting or finishing spray.