There are a few things you need to know before starting to plaster a wall: - The surface you're plastering needs to be smooth and clean. Make sure there are no bumps or lumps, and that all of the dirt and dust has been removed. If there are any cracks in the surface, you'll need to fix them before you start plastering. - You'll also need to make sure the wall is wet before you start plating. Mix up some plaster according to the instructions on the packet, then use a brush or a roller to apply it evenly across the surface of the wall. - Once the plaster has dried, you can sand it down until it's smooth.

There are a few key steps in plastering a wall like a professional. The first step is to make sure that the surface you're plastering is clean and dry. Next, mix the plaster according to the instructions on the package, then use a trowel to spread it over the surface of the wall. Make sure to apply an even coat and use smooth strokes. Finally, let the plaster dry completely before painting or decorating.