1. In the shower: Your hair probably gets oily quickly, so shampoo daily with a volumizing shampoo and conditioner. Paul Mitchell Lemon Sage Thickening Shampoo ($11.50; PaulMitchell.com for salons) is gentle enough to use frequently. Conditioner weighs down fine hair; apply it only from midlength to ends. Try Aveda Pure Abundance Volumizing Clay Conditioner ($15; Aveda.com), which has kaolin clay to make hair appear fuller.
2. When hair is still damp: Straight, fine hair falls even flatter when you use the wrong styling products. Stay away from oils, serums, or anything that boasts "extra hold"—these formulas can be heavy. Instead, choose a lightweight volumizing spray, like L'Oréal Professionnel Volume Expand Volumizing Root Lift Spray ($23; LorealProfessionnel.com for salons), and mist it only at the roots. Blow-drying for a few minutes helps the product create some oomph.
3. Just before you leave the house: Hairspray is drying because it contains alcohol; use it to reduce oiliness. TreSemmé 24 Hour Body Finishing Spray ($4.50; drugstores) provides hold without freezing your style in place, and also adds shine.
See the best cut for fine and straight hair in the summer