Wait for the adhesive to completely harden before grouting (this can take a day or two). If you can move a tile to the side using your hand, you need to wait longer. Use unsanded grout for joints less than 1⁄8 inch wide and sanded grout for wider joints. Unless the grout is fortified with powdered latex, mix it with liquid latex even if the directions say you can mix it with water only. Prepare as much grout as you can use in 20 minutes or so. In a clean bucket, mix the liquid latex or water with the powder (a margin trowel works well as a mixing tool) until the grout is free of lumps and about as thick as toothpaste. Wait 10 minutes, and then stir again.

1. Tilt the float up, and use it like a squeegee to wipe away most of the grout from the face of the tiles. Be careful to scrape diagonally so that the edge of the float cannot dig into the grout lines between the tiles.
2. Dampen a sponge, and wipe the tiles gently. Rinse the sponge every few minutes with clean water. If you see a gap in a grout line, push more grout into the gap using your finger, and wipe away the excess. Then wipe the surface two or three more times.
3. Run the sponge gently along the vertical and horizontal grout lines to make them consistent. If necessary, try running the rounded handle of a tool along each line. Allow the grout to dry, and then buff the surface of the tiles with a dry, lint-free cloth.