Redken Body Full is a spray in volumizer. This is one of my favorite products to give a boost of volume and you can buy a matching shampoo and conditioner to go with it!
When I use the Body Full on my clients, I first wash their hair and bring them back to my chair. Once I've towel dried it really good and went through the hair with a blow dryer for a minute to get the excess water out, I spray the Body Full in all around the crown area and the temples. When you blow dry, use a round brush or blow dry with your head upside down. It will amazingly boost your volume!