Instead of sitting on hold with the 1-800 operator, turn to these easy fixes for every color mishap. The things you'll need on hand: a clarifying shampoo, a conditioning mask, and a few pantry goods.
If your hair is too dark... Wash it immediately, says Wella Professionals celebrity colorist Jennifer J. If it's far too dark, mix a tablespoon of baking soda (which acts as a mild detergent) with a clarifying shampoo like Pantene Truly Natural Clarifying Shampoo ($5, drugstore.com) and let it sit on wet hair for five minutes. Or apply olive oil to damp hair, wrap it all up in a shower cap, and place a hot towel over it. "The heat opens up the cuticle just enough to let a few dye molecules slip out," she says. Follow with your regular shampoo ASAP.
If it's too light... You're going to have to add more dye. For hair that's just a little too pale, choose the next shade darker than the one you started with, and apply it only on the areas you think are too faint. Leave the color on for half the time indicated on the box, and keep checking to make sure it doesn't go too far. If hair is way too light, see a pro.
If it's brassy... You'll need to tone down your hair's warm tint. If you used semipermanent dye, try a lavender-hued shampoo like Clairol Professional Shimmer Lights Shampoo ($9, sallybeauty.com) for the next few days. If you went with a permanent formula, paint a shade that's two tones darker just on the orangey spots. Next time, go for cooler tones with a blue base.
If it turned green from dyeing (or it was exposed to chlorine)... Try washing the tint out with a clarifying shampoo or a deep treatment mask like Wella Professionals Enrich Moisturizing Treatment ($12, wella.com for salons) right away. If that doesn't do the trick, rinse hair with ketchup. The red counteracts the green, and the acidity helps neutralize the reaction.