Select the hair color that is most compatible with your life style. If you don't have time to redo your roots every 3-4 weeks, you may want to select a hair color shade that is only 1-3 shades lighter than your natural color. The closer you go to your natural hair color, the less your roots will show as they grow out. 

When your roots are less obvious, your hair color will last longer before you have to touch up your roots. Always select the type of coloring product that is easiest for you to maintain.

Apply a deep conditioning treatment to your hair a few days before coloring. The better conditioned your hair is, the easier the color will take and the longer it will last. Recently conditioned hair will also be softer and shinier. As an extra bonus, a deep conditioner will protect your hair against any possible damage from the color chemicals.

Color hair that has not been washed for 1 day. The natural hair oils will assist in making the hair color application more successful. The color will cling better to hair that is not dry.

Use a color enhancing shampoo between applications to enhance and maintain the color. The color shampoos like Mine, Manic Panic, ARTec  and Aveda's color shampoos are specifically designed to keep your color fresh as long as possible. Be sure to use the color shampoos religiously to maintain your color. The color shampoos will help you keep your color looking good until it is time for the next application. If you don't wish to use a color enhancing shampoo then at least use the most gentle shampoo that you can.

Avoid exposing your colored hair to the sun or chlorine in swimming pools. The sun may fade your hair color and the chlorine may damage the color. In some severe cases, if you have colored your hair a very light color the chlorine may leave a green tinge to your hair.

Keep your hair conditioned. Hair coloring will make your hair drier than normal. It is important to keep your hair conditioned and soft. Conditioned hair holds color better than dry, brittle or damaged hair. Conditioned hair also makes the colored hair shinier and brighter.

Add a temporary color to give you longer wear.  There are several wonderful temporary hair colors now available on the market that will give your hair a temporary color what washes out after a few shampoos. If the roots seem to be growing out a lot faster than normal, or the color looks a little faded, use a temporary color until your next permanent color application.

Use layered colors to prevent an overall faded color look. If your hair is colored all one color, or seems to fade fast after each color application, you may want to try a layered color look. The advantage to applying layered colors would be to have complimentary shades of darker and lighter colors which would reflect the light and give the color a multidimensional look. This would give your color a fresher, less faded look. It would also last longer because of the multiple shades woven into your hair.