Two words: dry shampoo. You need some, especially if you've got fine hair like moi. It's a must-have for making your fancy blow-out last—or if you simply want to get out of the habit of daily washing, which makes colour fade faster. It also gives your hair this wonderful next-day texture that I think can actually look better than squeaky-clean hair.
The problem with many dry shampoos (I'm looking at you, Klorane) is that they spray on white*. Unless you're a platinum blonde or very good at strategic application, this can make you look like you're going prematurely gray. That's one reason why my new favourite one is Ojon Rub-Out Dry Cleanser, which doesn't leave any chalky white residue. It also makes my hair feel cleaner than any dry shampoo I've tried, maybe because it contains oil-absorbing Amazonian white clay, silk powder and rice and potato starches.
* Bumble and Bumble, which I generally think is a fantastic brand, came out with a line of tinted hair powders a few years ago. But I don't love them. Yes, they solve the problem of grayish roots. But who wants to touch their hair and get chalky brown powder all over their hands? I need my dry shampoo to make me feel cleaner, and this doesn't.
To use a dry shampoo, you first need to shake it vigorously, otherwise it can clog. Then, holding it about 12 inches or so away from your head, spray it at your roots only. With Ojon's, you're supposed to gently rub it into your scalp and then brush to evenly distribute the product. It takes a couple of minutes to work so you'll probably want to finish with a final brush-out before styling.
Another trick to squeezing more mileage out of a blow-out is to wash your bangs only, then blow-dry them to re-style them. Be careful about getting the rest of your hair wet, though. A cute shower cap can help—I like Benefit's Bathina Shower Cap, which I can only find on their UK site. Please don't say it's discontinued, Benefit!
It's also helpful to sleep with your hair loosely tied back (and bangs pinned away from your face)—it will keep any waves in place and prevent hair from getting frizzy or greasy. But you can always refresh the top layers with a flat-iron or curling iron.
And finally, resist the urge to touch your hair. It transfers the oil from your hands on to your locks. So hands off!