Hose off any debris from the surface of the sidewalk, or use a power washer to force off embedded dirt and grime.
Patch the cracks and pits in the concrete with concrete patching compound. Fill deep cracks with sand until it is ½ inch from the surface, and then fill it with the patching compound, using a putty knife.
Place the tiles on the concrete surface and plan out your design. If the walkway is short, such as from the driveway to your front entrance, build from the center of the sidewalk outward. For a long or winding walkway, mix and match different colors for a mosaic look.
Draw a chalk cut line over any end tiles you will need to cut to fit. Place the tiles in a tile cutter, or use a diamond-tipped saw to cut them.
Fasten metal edging along the edges of the sidewalk by driving 12-inch spikes through edging slots into the ground. While you're installing the tiles, the edging will keep the tiles from moving. You can remove it once the mortar and grout harden or keep it in place for extra stability.
Mix mortar in a bucket with a small amount of water to make a spreadable consistency. Spread it over one end of the sidewalk with a ½-inch notched trowel. Lay down enough mortar for three to four tiles at a time.
Place the first tile in the mortar at a corner of the sidewalk, applying enough force to adhere it to the mortar. Place the next tiles next to the first, using the same method. Lay a board over the three tiles and lightly hit the board with a mallet to make the tiles level with each other. Set tile spacers in the corners of the tiles.
Continue placing tiles in the mortar in sections until the sidewalk is covered. Use the board to make each row level. Scrape off any excess mortar with a pointed trowel, and use a moist cloth to wipe away any spatters.
Wait one day for the mortar to set, and take out the tile spacers.
Make a stiff, pasty batch of grout in a bucket with equal parts sand, cement and a small amount of water. Press the grout into the spaces between tiles, using a grout float. Sponge off any drops as you go, and dip the sponge in a bucket of water frequently to keep it clean.