The first step is to read my How To Clean Grout instructions. After the grout has dried exposing the true color, you now have increased your odds in finding a color that will match. You can get free grout samples at the local home improvement store but keep in mind that there are 2 or 3 really common grout brands out there which lessens the odds of choosing the exact brand and color of your grout. No worries, I do this all the time and personally use 2 brands of grout. I have noticed that there are some similiar grout colors between brands so I just find the color that best matches. The real key is to make sure and clean that grout! This is exactly how a ceramictilepro matches grout and now you can too!