I use normally use Mr. Clean or Pinesol or any other commercial floor cleaning product. Dilute in a bucket of water and use a sponge mop. We have darker tile with a dark grout. Sealed the grout with a silicon based product. 10 coats (yes 10!) of that stuff with a kiddie paint brush but well worth it. It's been over 20 years and you can still see the seal on the grout an no dirt!