You need a vented brush.
Give the can a good shake. Then pump a tennis ball-sized puff directly onto the brush (not your palms!) before combing it through damp (not sopping wet!) strands. Get into your roots with the mousse. It’s meant to boost volume there the most.
The mousse will slowly seep through the vented slots so that it gets evenly distributed as you brush (as opposed to uneven application from your hands).
For extra lift, pull your hair at ninety degrees from the head with short, repeated strokes will you dry it.
You get zero crunch once dried. It also helps to perk up limp, day-two strands. Just re-wet, reapply and blast your roots with a dryer.