-Lighten hair to the correct level. The lighter or brighter you want your color to be, the lighter the hair needs to be. For darker tones or oil slick looks, you can be as dark as a 7 for great results. So make sure your base is correct for the results you are trying to achieve.
- Did you lighten to white? Is the hair maybe pretty porous? Is it maybe a good idea to do a porosity filler on it so all the color doesn't immediately fade out? Yeah, try that - it makes a huge difference!
-When you rinsed out the bleach, did you shampoo not once, but twice? ANY bleach residue on the hair can mess up your results and make your color splotchy. Give it an extra wash just to make sure you've got a squeaky clean canvas.
-When you rinsed out the bleach, did you skip the conditioner? SKIP THE CONDITIONER. You can condition later, after you color it. Conditioner has lipids in it (waxes and/or oils) and these can block the absorption of non-oxidative color. Yes, it will probably be tangly when you get them out of the bowl. Just blow dry those out. Seriously. Your blow dryer can detangle hair. Try it.
-Did you dry the hair before you applied color? Dry the hair. Some directions suggest applying on damp hair, but in my experience, this almost always leads to diluted color that isn't as vibrant or long lasting. It doesn't hurt anything to apply it to dry hair and it gives better results, so just do that.
-Did you fully saturate the hair? Don't skimp on this stuff! Glop it on there for maximum vibrancy and evenness.
-Give it 20 minutes with heat, then 10 minutes without before you rinse. Heat opens the cuticle, which is great for getting that color in there. But you want that cuticle closed back up before you rinse so all the color molecules don't come sliding out immediately.
-Speaking of closed cuticles, make sure you are rinsing with the coldest water you can tolerate! COLD!
-No shampoo this time - just scrub really good with both the water and the conditioner. Their hair already got shampooed twice after bleaching. They'll be okay.
-Send them home with color safe, sulfate free shampoo.
-Make sure they know not to wash their hair every day. Every other day or every few days is fine; this will vary a bit depending on everyone's individual scalp oil levels.
-Make sure they know to use cold water to wash and rinse. And when they are standing in the shower doing anything else but washing their hair, clip that hair up out of the hot water!
-Make sure they know that lots of sunlight and swimming - in chlorine OR salt water - will strip color out.
-Make sure they are using heat protectant products when they heat style - this can also fade color.
-Make sure they understand that they are spending A LOT of time and money on their hair, so taking care of it when at home is the best way to maximize that investment. It also makes you both look good - they have good, long lasting color, and you look like a competent stylist whose clients trust them. Win-win!