1. Honor Thy Hue
"Use your current color (even if it's dyed) as a gauge when selecting your formula-and never lighten or darken your hair more than two shades at one time," says Rachel Glenn of Chicago's Prink Salon.
2. Thou Shalt Keep Thy Cool
Lightening tresses with a "warm" formula may leave you brassy. "Opting for a color described as 'cool' or 'neutral' is a safer bet for first-timers," says Jason Backe of Manhattan's Ted Gibson Salon.
3. Thou Shalt Not Skimp On Dye
Imagine running out of dye halfway through color application. Not good. The amount in most kits is sufficient for the "average" head of hair (about shoulder-length). So, cautions Patty Slattery, director of L'Oréal Technical Center, "If your locks are longer or very thick, stock up."
4. Thou Shalt Splurge On Tools
The application tools supplied by most kits are pretty flimsy. If you want the job done right, says Backe, pick up pro tools at any beauty-supply store. MC recommends: Spontex Vinyl Gloves, Color Trak Caddy Bowl and Brush
5. Honor Thy Strand Test
Save yourself after-color anguish (and a hefty color-correction bill) by doing a strand test on your underlayer before coloring your whole head, says Slattery.
6. Thou Shalt Touch Up with Caution
"Mismatched roots and ends are a dead giveaway that you dye your own hair," says Backe. "This happens when dye dribbles down from the roots and oversaturates already-colored ends." Better to get a friend — or a three-way mirror — to help you confine dye to the regrowth area. Need to refresh the rest of your hair, too? Wait until the last five minutes of the process, then run color down the shaft.
7. Thou Shalt Not Trash Thy Tresses
"The more you baby your hair, the better it maintains new color," says Slattery. So choose shampoos formulated for color-treated tresses and deep-condition at least once a week. MC recommends: Kérastase Reflection Bain Miroir Shampoo and Chroma Reflect Masque
8. Thou Shalt Age Gracefully
"To cover grays, choose an allover shade that falls between your new silver strands and the color you had as a child," says Slattery. "This softens your face and camouflages regrowth."