Look for signs of mold or damage to the tiling surface. Cracks are often a sign that a wall may be weak and need to be replaced. Try pressing on the wall, especially at the studs. If it gives way or feels soft, it may require work. If you are going to be tiling a large area, remember to use tiling board as a backer and not just put the tiles directly onto drywall. [1] X Research source Tiling board is installed just like drywall (nailed to the studs) but is made of more water resistant materials which will keep it from warping and cracking your tile work. [2] X Expert Source Art FrickeHome Renovation & Repair Specialist Expert Interview. 1 July 2020.

Never assume a fixture in the room like the tub or vanity (or even the ceiling) is perfectly level. They rarely are. It is very important to rely on the level.

You can use just regular string and manually chalk it to make a chalk line. Using a chalk box may be easier as these take less work - you can buy one for about $5.

So, for example, let’s say your wall to tile is five feet long. You’re putting up subway tile and the tiles are 6", with spaces of 1/4" between each of them. You’ll need 9. 6 tiles for each row to cover that space, meaning nine full tiles and one cut to 3. 6" If you don’t own a diamond tipped wet saw, you can usually rent one from your local major hardware store. You can also use a tile cutter, but this is more likely to end in broken tiles so only take this option if using cheaper tiles. [4] X Research source Dry fitting is especially important if your tiles make up a pattern, since you will need to be very comfortable creating that pattern. You don’t want to make a mistake or have to spend a lot of time thinking about it once the mortar is up on your wall. You can test your dry fit pattern by making a layout stick, which can be made from any straight and level piece of spare wood. Lay the tiles on a floor and mark the layout stick with a pencil at the joints between tiles. Use the layout stick to see how the tiles fit on the wall.

Double check that everything is level before installing the tiles on the batten. You’ll also want to check it all the way across, since there may be dips in the wood you use for your batten.

You should also allow it to “slake” after you first mix it up. This means you allow it to rest for 10-15 minutes and then stir it up again. Now it is ready to use.

Your trowel size will depend on the size and type of tile you’re using. For the average small wall tiles which are currently popular, you will want to use a 1x4" square notch trowel. Test a tile to make sure the mortar is mixed and spread correctly. Mortar a small spot and then place a tile. Pull the tile up and look at the pattern that is create on the back. If you see clear lines, then the mortar is too dry. If you see goopy mounds then the mortar is too wet.

If the mortar rises up between the tiles as you place them, the bed is too thick and you will need a smaller trowel. Check the tiles for level as you go. This is when a laser level can really come in handy.

Sanded grout is used for gaps larger than 3mm. Unsanded grout is used for gaps smaller than 3mm. You can find all sorts of additives at your local hardware store. These can do everything from making the grout more water resistant to changing the color to match your tiles.

You do not want to push the grout around parallel to the lines, since this can gouge the grout back out of the gaps. You can save yourself some time by using the grout float to remove as much of the excess grout off of the tiles as possible.

It is best to do this for each small area as you complete it but you can wait until you have done two to four small areas as well. Keep in mind, however, that it will be much harder to get the grout off and the final look may not be as professional.

Some additives may cause the grout to cure more slowly. See the included packaging for any addendums to the curing process. You can clean off any remaining residue after the grout has cured. An old sock or dry rag work well for this.

You can also get brush-on or spray-on tile sealer. Do not put these sealers on non-glazed, unfinished tile. It will absorb into and possibly stain the tile.