I'm not a fan of at home dye jobs and I gave my two cents in this article - unless you're going to stay within a color level that is close to your natural shade.
Even then, it is so important to get the color on the roots only, in the beginning of the application, and then bring it out to the ends at a certain point and truly, a hairdresser is the only one who knows how/when to do that properly.
Let's be real. We can usually tell when someone is coloring their own hair. We've all seen it. It's not usually very pretty.
But, if you simply must and cannot help yourself, there are some great tips in this article.
If you need a little touch-up before you can get to the salon, I love this little gizmo. The color stays put until your next shampoo.