I use a spray-on volumizer sometimes.  Sometimes when my hair is dry I will wet the roots a little and then spray some volumizer on the roots.  Then I bend over at the waist and let my hair hang and blow dry just the roots on the warm or cool setting. 

I used to do this often after washing, but now I almost never blow dry my hair.  If you blow dry your hair, this could be another method.

The volumizer provided a little lift.  The problem for me was with my fine-ish hair, if it was just hanging straight, it would kind of stand up and make parts in my hair.  I wasn't looking for a sneak peek at my scalp, I was looking for fullness.  I still use it for some styles.

I found that if I applied it all over the hair, it would provide a fuller look, but it would kind of gum up and cause tangles.   But it is great for certain styles, I just won't try to put a comb through it until after conditioning. 

I never use it anymore until the last day before washing, but the effect can be fun.

rhp