In the setting out stages, it's important to make sure the tiles look straight from the entrance to the room. Often walls are bowed or out of true so check your measurements in several places along each wall.

1. Find the midpoints of the two longest walls. Stretch a chalk line - a length of line covered in chalk - across the room between these points and 'snap' it, tugging it sharply so that it snaps against the floor, to mark a line on the floor halfway along the room. Repeat for the shorter walls but adjust the line so that it passes through the centre of the first line at right angles.
2. Try to work with as many whole tiles as possible, even if it means adjusting the grout line width slightly. To do this, you could either use thicker spacers or simply make the gaps between the last few rows of tiles at the most inconspicuous end of the room slightly further apart or closer together.
3. Lay tiles along the two lines to check they look right from the doorway. If any gaps at the walls are less than half a tile wide, shift the line across to make more of a gap.

Floor tiles are often easier to lay than wall tiles as there's usually less cutting around awkward shapes and you're not fighting against gravity.

1. Spread about 1 sq m (10 sq ft) of tile adhesive or combined adhesive/grout into one of the right angles made by the two crossing chalk lines.
2. Scrape the notched edge of the spreader across the mix to form ridges of the same thickness.
3. Lay the first few tiles along the edge of the longest centre line. Gently press the tiles into place, making sure they also line up with the other centre line. Add plastic spacers at each corner.
4. Work outwards from the middle of the room until you have laid all the whole tiles on one half of the floor, using a spirit level over every three or four tiles as you lay them to check the tiles are at the same level - not necessarily perfectly horizontal but all surfaces should be flush.
5. Then move across to the other side of the longest centre line and add the rest of the whole tiles.
6. Leave to set for 24 hours - don't walk on the tiles during this time.
7. Use the tile cutter to trim the edge tiles to the right shape. Measure the space at both ends of each run of wall in case the walls are uneven, and remember to allow for the grouting gap. Always wear safety goggles and gloves when you are cutting tiles.
8. Leave the adhesive to set for at least 12 hours, then seal the surface if necessary and allow the sealer to dry for at least two hours. Ceramic floor tiles don't need a coating, but unsealed stone, terracotta, slate, and quarry tiles should be protected with a sealer, available from tile stores or DIY centres.
9. Grout between the tiles. Force the grout into the gaps with a squeegee, working from side to side and up and down the tiles. Wipe any grout from the tiles with a damp sponge before it sets hard.