Where to start
If you're tiling an entire wall or floor, it's usual to start as near to the middle as possible and work outwards.The experts have a complicated way of finding the exact centre by banging a 'chalk line' across it. However, you can get a much easier (although marginally less accurate) guide by drawing two diagonal lines from each corner of the wall or floor to the other. Where they cross is your start point. However, if your door, say, isn't central to the room this method may not be the best solution, and it's at this point that it maybe wise to call in the professionals. Remember, tiles aren't cheap - and if you mess up and have to start all over again, it will cost far more than it would have to call in an expert in the first place.

The usual rule of thumb is that if it's a relatively simple job you can do it yourself, although you must get advice on the correct adhesive - bathroom tiles, for instance, need waterproof grout.

Which type of trowel you buy depends on the type of tiles you're planning to lay. Floor tiles, for instance, are generally bedded in a thicker layer of adhesive than wall tiles, so you need a more heavily grooved trowel. Check with the retailer that the one you're buying is suitable.

It's also wise to check when you buy that your tile cutter can handle the particular type of tile you're planning to lay. Floor tiles in particular are thick and can be difficult to cut through. Cheap tile cutters often cause problems because they only scores the surface, and imperfectly at that. Consequently when you try to snap the tile it breaks. It doesn't cost much more - usually less than £5 - to buy a tile cutter with a built-in snapping mechanism which is virtually foolproof. Buy the best tile cutter you can afford: it will make the job so much easier.

If your task involves curves or pipework you may also need a special "coping" saw (with a rotating blade to cut angles), tile pliers or nippers, a special drill bit to cut holes or even an electric tile saw (from £50). Go to a specialist tile retailer, where the staff will be trained to help you make the right choice.

If you don't want to spend out money for what maybe a one-off job, then remember that these days you can hire professional quality tools at minimal cost from hire shops and some leading tile stores. Do follow the safety instructions provided at all times, though.

The tricky ones
You should call in an expert if:

you have to cut around pipework, plumbing fixtures, sanitaryware, electric sockets or kitchen units and appliances you want a fully tiled shower enclosure you are using small, hand-made or very large tiles your walls are in any way bumpy or of unequal height.

Tools of the trade
The basic tiling tools are:

a bucket for mixing the adhesive (or buy ready-mixed paste) a notched trowel for spreading the adhesive tile spacers a tile cutter a grout applicator (such as a rubber-bladed spatula) a sponge to clean off the excess grout.

Buying tiles
It's always best to buy tiles from a dedicated tiling specialist - either a local independent shop or a multiple retailer. These are the experts and they should have trained staff who can offer useful, practical advice. Many offer valuable customer service initiatives like free "how to tile" videos, free samples, free delivery, a "buy back" service, tool hire and free estimates.

Project
How to tile over existing tiles

First tap all tiles lightly with a mallet to make sure they are sound, flat and properly stuck to the wall. Those that are loose will sound hollow and should be removed and stuck back in place with the appropriate adhesive. Clean tiles thoroughly with soap and water to get rid of grease and soap scum, and allow to dry prior to tiling. There's no need to score old tiles. It doesn't matter whether you stick them exactly over the old tiles or not as long as they're on a good bed of adhesive. The joins of the old tiles can be useful as a guide to checking whether the new tiles are exactly horizontal and vertical. Remember that in effect you are sticking tiles onto a surface as slippery as a sheet of glass. You need them to remain in place so use the correct adhesive for the job - ask the retailer if you're in doubt. Unless your tiles run right up to the ceiling you may be left with a protrusion at the top. You can mask this with a suitable edge strip, such as a moulding, or listello, or with a band of mosaic tiles in complementary or matching shades.

Tricks of the trade

If money's tight and you want to give your room a designer look at a fraction of the cost, then combine cheap tiles with a few expensive ones. Be careful about the depth of the tiles and their dimensions if you mix and match on the same wall. Also avoid mixing rounded and square edged tiles - they will look like a mistake, not a design statement!. Thin strips of eye-catching decorative tile - sometimes flat, sometimes moulded - are known in the trade as "listellos". These can be used as a dado rail or a decorative edge to worktops or baths. Listellos come in ceramic, glass, stone, mosaic, metal and combinations of different materials. Used cleverly, they'll lift any tiling scheme. Buy cheap, plain tiles in bright colours and create your own ceramic collage, in either a random or formal pattern. Try a bold orange moulded listello and lay a mix of warm Mediterranean colours - yellows, oranges, apricots and reds - above the dado. For a seaside theme, choose a pale aqua listello and mix with different shades of blue and green. Fuschia pink can look pretty with shades of lavender and paler rose pinks, while cream, beige, grey and stone will give a sophisticated feel.

Are tiles good for the garden?
Outdoors, tiles are a brilliant idea, but there are a few basic rules you should follow. First, only use frost and slip-resistant tiles. There is a vast range suitable for external use, which because they do not absorb moisture are totally frost-resistant. You can get simulated terracotta, limestone, sandstone, slate or marble, in a variety of textured, slip-resistant finishes. Once you've seen the eye-catching results that can be achieved you'll never use concrete paving slabs again!

Avoid dodgy dealers
Rogue traders are a problem across the whole building industry and the tile trade is no exception. However, there are many excellent, professional fixers in the UK. To find someone you're happy with is important because they're going to be in your home, so ask friends, your builder or your local tile shop for their recommendations. Get two or three quotes, and trust your instincts: if you're unsure about a contractor, don't give him the job! Remember, the cheapest isn't necessarily the best.

Recently, The Tile Association (TTA) introduced its Members' Guarantee to give the consumer confidence that they'll be compensated through the organisation's insurance scheme if anything goes wrong. For more information, contact TTA on 020 8663 0946.

At a glance

Plan in advance. Measure up meticulously (with old houses it's best to measure the length and breadth of the room along all walls, as rooms are often an irregular shape). Add on an 10% extra for breakage and cutting. Make sure walls are flat, sound and free from defects. If not, either make good with filler or apply a specialist tile backing board, or 12-18mm marine plywood treated with a suitable primer. Get advice from the tile shop on the correct adhesive. When tiling walls or floors, it is usually best to measure the central point and work outwards. When using coloured or patterned tiles, lay out your design first so you know exactly what is going where. When tiling splashbacks or windows, centre the first two tiles and build out from there to give a professional, balanced finish. To ensure a straight run of tiles on walls, mark on the wall the height of the first tile. Then attach a piece of wood which is long enough to run the full length of the wall you're going to tile. This is your horizontal reference point, and the tiles build up from that base line. Only apply 1 square metre of adhesive at a time and slide the tiles into place to ensure good bedding. They should be separated by matchsticks or plastic crosses (called spacers), available in a range of thicknesses, which ensure regular spacing between the tiles. This is where the grout will go. Prevent breakage when cutting complex shapes by only nipping off small pieces of tile at a time. Wear protective glasses when cutting tiles, and beware of sharp edges on cut tiles. Allow the tile adhesive to dry thoroughly for 24 hours before grouting. If you're a novice and doing the tiling yourself, read a good DIY tiling guide first, or log onto www.tiles.org.uk.