When I was worried about boosting hair volume (without drastically altering my hair regimen, which is shampoo, conditioner, wet-combing, and air-drying), my hair stylist recommended using a round brush. I know, it's a totally radical concept. She also said things like "learn how to use a hair dryer" and "perhaps buy some volumizing product" but I ignored all that.
Then I started researching what kind of round brush to buy. The stylist had mentioned boar's hair bristles, which sounded a little odd. But I read up on boar's hair and was convinced. ("Boar bristles are easier on hair than cheapie plastic brushes and they redistribute oils throughout hair, boosting shine.")
Spornette seemed a good fit- recommended by In Style magazine, and without the crazy Mason Pearson price.
I wait until my hair is completely dry before flipping my head forward and briskly brushing my hair. Actually I should probably use it a little more gently, and try to tug less on the scalp. My hair does have more body and bounce, which is good, because I don't know how to operate (let alone own) any type of hot iron hair tool.
I chose the "813" because the size was about right for me, 1-3/4" diameter. They have smaller brushes (too piddly) and larger (mammoth ones which look vaguely menacing). This is just right for me.
The one thing I need to do is take better care of this brush :-( . It stays in my bag, and seems to accrue a good amount of lint and dust along with the actual hair. And I keep forgetting to clean it. (I'm looking at it sadly right now.)