This can quite easily overload your sockets in the wall. Modern items such as TVs, Blu-Ray players, Sky boxes, Playstation/Xbox, all use a wide selection of plugs and adapators. Even having table lamps, reading lamps and such like can be fighting for a socket.
Additional sockets fitted in your property mean that you can ditch the tangle of extension leads. A good upgrade to begin with is replacing any single sockets with double sockets. This means you have doubled the number of those straight away. This is relatively straightforward and involves less wall chasing/mess than fitting extra sockets in places they have not been before.
Sometimes the main issue with the sockets is you do actually have already is that they are in the wrong place! Again, if your TV and all the stuff that goes with it are at the opposite end of the room to your existing socket outlets then again, the usual solution is a patchwork of extension leads, often stretched behind sofas & furniture.
The advent of smart phones, tablets and wearable technology has brought another demand for USB outlets. If your home does not have any built in USB outlets in the sockets then you will loose a precious 13A socket to an adaptor. This brings us to the solution of: