I've said it before and I will say it again-I think haircolor should be left to a professional. There is a reason we go to cosmetology school and have to get a license to do hair. A lot can happen to your hair when you color it and if you don't know color theory there is a great potential for disaster. With that said, I totally understand that getting haircolor done professionally isn't always an option for everyone and you need to do it at home. Here is my advice take it or leave it.
First, if you are going more than a few levels darker or going lighter you really should see a professional because going lighter at home usually results in an orange color and going more than 2 levels darker gets tricky because you need to add back or "fill" the hair with the missing colors. So, if you are sticking around the same level or going a bit darker you should be fine.
Next, please, please, please don't use box color from the grocery store or drug store. You can get professional color from places like Sally's Beauty Supply. The results with professional color are going to be so much better and you aren't putting crap-like metallic salts on your hair. Also, if you decide to go see a professional hairstylist the professional haircolor is so much easier to work with than box color. Some box colors you cannot color over or remove because what is in them will make your hair BREAK OFF!
Last, don't be fooled by the highlighting kits. They might look easy to use, but I've yet to see someone do a good job with them. Most people end up with polka dot hair. Happy coloring!
Your friendly Hair Girl,