It might not be the best way to add volume, but mine often poofs out a bit more if I go to bed with it damp after a shower. It's unpredictable, though, so you should probably go with whatever other advice you receive before trying that.
Uhhh, I have short hair so let's see what this does for you. Try it on a weekend. but. After getting out of the shower, take a towel, and rub it in your hair really good too where it's all messy. comb it into place with your fingers and then mess it a bit more and comb it in place with your fingers again. let it dry, and keep an eye if anything gets out of place. Usually if I comb my hair straight out of the shower it's straight, and flat. but if I do that it's poofy and kinda wild.
This ^ Thats what I do. I put mousse in and blow dry it upside down. Works like a charm. Also, I try to use only the minimal amount of conditioner. It weighs my hair down because it's not very thick.
Go for a swim in the ocean and don't wash your hair after ^^ The salt, sand and minerals will do your hair wonders as well as giving you the desired 'poofyness'.
you could tease it, take a portion of it, and comb the underneath part of it, but instead of going toward the tip go toward the root, this makes it less flat, but tangles it. If you use lots of conditioner before you shampoo and brush your hair while in the shower the tangles come out too