Knowing how to prep a wall for painting is important to really be able to get the best result of the new paint later on. It is pretty much the same as in dealing with repainting project. Basically the old layer of paint should be stripped and cleaned first before making the surface read for the new paint.
Since it is a wall, stripping the paint should be done properly so that the surface of the wall will really be even. There is a specific tool for that matter which will be needed along the way when removing the old layers of paint on the wall.
Once the old paint layers have been removed then the wall should be sanded to make sure the even surface. The sandpaper used for the wall may well be in various levels depending on the need of sanding. It may well be repeated in term of sanding and applying the primer.
Next thing is to actually apply a primer for the paint so that the paint could really stick to the wall and that the true color of the paint will be nice. The primer should be the one in high quality in order to maximize the result of the paint itself.