Preparing a room for decorating is probably the least exciting aspect of the job, however it's the most important. You need to ensure that your surfaces and walls are in perfect condition before you decorate to get a smooth and long lasting finish.
Needless to say the first step is to ensure that all your furniture and loose items are covered, your plug sockets covers are unscrewed, and use insulation tape to cover switch covers and light fittings. Now its time to concentrate on the walls -
If you have minor damages in your walls, small holes from nails or hairline cracks, be sure to fill them before painting. Fillers are easy to use and available as dry powder to be mixed with water or ready mixed in a tube. Simply apply it with a scrapper, but bear in mind is shrinks when it dries so leave it protruding a bit. Water resistant fillers are also available for bathrooms, windows etc.
When you are painting base coats are a necessity. Base coats are made up of thick paint augmented with fillers and plasticisers so that they fill and cover cracks and imperfections on walls and ceilings and also block stains from bleeding through. They are simple to use, but must be applied with a fluffy roller, which gives a textured finish. If you’re painting over dark colours it’s important that you use a primer, and professional painters often tint the primer by mixing a little bit of the topcoat paint with the primer. This enhances the topcoats ability to hide the primed area.
If your walls are a bit battered or have an uneven surface, skimming is your best option. Skimming involves putting a thin coat of plaster on top of existing plaster and is the best way to achieve a smooth finish. Skimming is generally a job for a professional plasterer, as they will (hopefully!) do the job quicker and neater than you would do yourself. Also a coat of PVA is applied to the wall to provide something for the plaster to stick to, which is something best achieved by a plasterer.
If you have large holes or cracks in the room don’t try to tackle it yourself as it may end up costing you more money in the long run. Get a professional plasterer who has an expansive knowledge of these things to take off the old plaster as well as apply the new one. But make sure you wait until the plaster has completely dried out before you paint it, which can take anywhere between two and seven days.