Step 1: Color your hair often
To keep your hair color looking great, you really need to color or highlight it every six weeks -- and if you are using red dyes, you might even need to do so as often as four weeks. (Red dyes fade faster than other colors because they are more sensitive to the detergents in shampoos.)
Step 2: Use a clarifying shampoo before coloring
If you use hair serums and other silicone-based products, use a clarifying shampoo for a few days before coloring your hair. Don't use a clarifying shampoo on a daily basis because it will fade your color. But use it before coloring to get the serums and silicones off your hair so that the dye will be able to penetrate more easily.
Step 3: Don't shampoo right after
Don't shampoo at all for 24 hours right before coloring your hair. If you hair is slightly oily, the dye will better adhere to your hair and last longer.
Step 4: Don't shampoo every day
Your color will fade more quickly if you shampoo daily. Most of us are in the habit of shampooing every day, but for most of us, our hair doesn't really need it. You can rinse your hair with cool water every morning and condition the ends if you need to do so. However, when it comes to protecting the hair strands, you should try to shampoo every other day rather than daily.
Step 5: Use a color-enhancing shampoo
When you do wash your hair, use a shampoo that will care for your color the way you want. If your hair color tends to get brassy, use a violet-based color enhancing shampoo and conditioner. The violet hues will combat the gold and orange brassy undertones that many women hate.
Step 6: Don't use hot water
Hot water will fade your hair color, so wash and rinse your hair in cool water. If you can't stand cold water, even lukewarm is better than hot!
Step 7: Skip the hairspray
Hairspray coats your hair, making the color look dull and lifeless. Get a haircut that allows you to limit your use of hairspray and gels. Save the hairspray for special occasion hairstyles.
Step 8: Protect your hair from the sun
If you are going to spend extended periods of time in the sun, wear a hat or scarf. If that's not practical, use shampoo and conditioner with built-in sunscreen. If you can't find such products, mix 1/2 cup water with a teaspoon of SPF 25 sunscreen in a spray bottle. Spritz the mixture on your hair after getting out of the shower each morning, and you should be set all day long!
For more tips on coloring and highlighting your hair, see:
The 10 commandments of sinfully rich hair color and Tips for coloring your hair at home