Another trick for avoiding frizz is to make sure you have a either have an oil or leave in conditioner handy before you allow it to air dry. I agree on tossing it up side down and shake it. this will help volume with out frizz. we all have our own tricks but i mix oil + leave in and it works like magic.
I agree, never comb your hair when dry. Only comb it wet and ideally with conditioner in. Try to touch your curls as little as possible when they're dry so as not to disturb them or create frizz. For adding volume to your already-dry hair I suggest flipping your head all the way forward and then using your fingers to shake up your curls right at the scalp. This method really works and you can do it any time throughout the day when your curls are looking flat.
I have also used the Q-Redew to give me more volume on my third and fourth day hair.
DO NOT comb or brush your hair when its dry. If you do, it almost guarantees that you will have frizz. Only comb/detangle when wet, preferably with a bit of conditioner in it. To get volume you can try using a diffuser attachment on your hair drier when your hair is still pretty damp. Flip your head over and use the diffuser or shake your head to toss your curls while drying. Don't use your fingers or anything to comb or rake through your curls or all the nice curl clumping will get broken up and become frizz. If you prefer to air dry you can use clips at your roots to get some volume like in these examples: