Ceramic tile and porcelain are very easy to clean. Sweep or vacuum as needed and mop with a mild detergent (like Spic-N-Span or Mr. Clean) or ceramic tile cleaner. Don't use harsh abrasives.
Now it is time to seal your grout. Sealing your grout will make the grout less porous and more resistant to discoloration. Manufacturers recommend sealing your grout once a year to keep it looking its best. You can purchase grout sealer at Enhance Floors & More.
Also check any caulking. Caulking is used where the tile is exposed to water. Caulking prevents expensive subsurface damage. Recaulk wet areas as needed.
TIP: Don't use bleach or ammonia based cleaners, as these products can discolor your grout.