The best-painted walls are only as good as their preparation. Time spent cleaning and making good walk and ceilings prior to receiving their finish is time well spent. As a general rule, although some paint finishes will disguise an uneven wall, the aim of careful preparation is to ensure that walls and other surfaces are as flat and smooth as possible. Paint and wallpaper are not just decorations; they also protect the surfaces from wear and tear. But these finishes may crack, flake, tear or fall off the wall if the surface is not prepared carefully. For a perfect finish, make sure the surfaces are clean, dry and free from crumbling plaster and flaking paint.

The first task is to clear the room of furniture and furnishings: take down curtains and, where possible, roll up carpets. This will give you a clear space in which to work, and will avoid damage should there be an accidental spill. Don't forget to remove light fittings and shelves, and if there is anything left in the room, move it to the centre and cover it with a dustsheet. Cover the floor with newspaper - but not in areas where you will be heat-stripping paint.

Painting over wallpaper is a quick-fix solution, but the results aren't always very good, because paint can soften the existing adhesive and cause it to start 'bubbling'. Stripping away old wallpaper can seem a daunting task, but some modern wallpapers, including most vinyls, are called 'easy strip', which means you can simply pull away the wallpaper leaving the backing paper in place.

Try lifting a strip of wallpaper in one corner to see if it will pull away. If it does and the under paper is in good condition, leave the under paper on the walls to serve as your lining paper. If the under paper is damaged or creased, then you'll have to strip this off as well.

There are two main methods of removing existing wallpaper and the layers of lining paper underneath. The first is by hand: if the wallpaper will not pull away, or the backing vapour is damaged, give it a good soaking with warm water with a little washing-up liquid and a handful of cellulose paste mixed well together. The washing-up liquid acts as a wetting agent and the paste holds the warm moisture in place while it softens the existing adhesive. Apply the solution to the wall with a wide brush or a roller and give it plenty of time to soak in.

Use a scraper and start peeling off the wallpaper. If it had a wipe-clean surface, or has been painted over, then you'll need to break up the surface by scoring it with a serrated scraper and then wetting it.

Don't be tempted to use a wire brush - you'll end up with tiny rolls of wet paper that will dry like concrete on the wall plaster and you might also get rust posts on the surface of the new wallpaper.

Steam Stripping

The second method of stripping wallpaper is steam stripping. This is best where layers of paper have been added on top of each other. Don't try using a boiling kettle and an old steam iron; not only is this dangerous, but it also doesn't work. Steam strippers can be hired easily and cheaply from tool-hire stores and are simple to use. Steam stripping is best done on a dry day when you can open the windows - otherwise you'll end up with a sauna in your house. Remember that the steam is hot, so wear gloves at all times. While steam stripping is quicker than doing it by hand, you'll still need to work slowly and carefully, especially if there is any loose plaster around, as even the lightest of steamers can gouge into the wall. The technique is to hold the plate close to the wall and allow the combination of heat and steam to soften the paste. This way - in theory - you should be able to scrape away several layers in one go. In practice, however, be prepared to steam over the walls again - particularly where strips of paper have been overlapped.

Don't forget that steam condenses into water so pay extra care and attention when you strip wallpaper from around electrical sockets and light switches with a steam stripper. For safety's sake, identify and isolate the power and lights in the room in which you are working. Don't just switch them off at the wall, turn off at the consumer unit too to avoid the risk of water coming into contact with live wires. Let the walls dry out thoroughly before you return the power to the room. A room that has been professionally wallpapered will have had the light switches taken off so there are no visible edges of the cut wallpaper - these are masked by the faceplate. You will have to remove the faceplate to strip the paper off cleanly. Where the wallpaper has been cut around to fit the perimeter of the faceplate, a very light steam should be enough to lift the paper so you can pull it away.

Washing Down Surfaces

Always wash your surface after stripping and before applying paint or wallpaper. Start with the ceiling, if it's in good condition. Wash it thoroughly with sugar soap, or a weak solution of warm water and washing-up liquid, and then rinse it well. Washing is particularly important in rooms such as kitchens where grease will have been deposited. Open fires and cigarette smoke will also leave their mark. Walls should always be washed if they are to be repainted. If you're not sure if an existing wallpaper is washable, do a test on a small patch where it won't show. If the paper absorbs the water or the pattern is affected, the wall is not washable. Wash by sponging and rinsing overlapping sections - and don't stop until you've finished, otherwise you'll end up with 'tidemarks'. Skirting boards are the dirtiest part of the walls, so always clean them last.