I don’t really like giving general hair advice and recommending the one product to everyone, but if you think you have hair like mine and want it to look/feel more thick, then the Thickening Tonic from Aveda will work. This is what I usually do to give it a bit more VaVavoom:
Spray all over,
Dry hair upside down with hot air
Then put the cold air on it (head still upside down) to make the volume set.
Shop it Here