Serving size: A silver dollar

Too much leave-in conditioner will leave hair limp and dull, says Swayze. Start at the ends and avoid the roots. You may need more product if your hair is longer than a few inches past your shoulders and less if it's shorter.

Serving size: An apricot

"When deep conditioning, your hair should be thoroughly coated and then some," says Swayze. After applying, cover hair with a plastic cap, which allows the conditioner to penetrate more into the hair shaft.

Serving size: A grape

"Using too much could ultimately dry your hair out," says Swayze. Concentrate the product on the most damaged areas.

Serving size: A quarter

More than a quarter and you risk crunchy hair that's hard to style. For smooth application, massage the gel in your hands first to avoid clumps.

Serving size: A mandarin orange

"Too much mousse in one area and you won't be able to get the brush through it," says Swayze. Apply it to the roots first, because that's where you want the most lift. Comb the product through before blow-drying.