Surface preparation is one of the most important factors in how good your paint job will look and how long it will last. Make sure the surface is clean and dry. Since your goal is a smooth finish, that's how the surface should be before you start. A layer of paint is very thin, and even tiny bits of dust will show through. If you've sanded the surface, and need to remove sawdust before you paint, most paint departments will offer a product called a tack cloth. This is a piece of cheesecloth treated with a substance that makes it sticky. Rubbing it over the surface removes bits of dirt. Keep folding the cloth over to expose fresh areas, and you can get a lot of use out of a single cloth. For walls and other areas where a textured finish is in order, it doesn't have to be smooth, but it still has to be clean. Oily areas should be primed with shellac (* shel-LACK) or other sealer to prevent bleed-through. Sand glossy areas lightly to dull the finish so the new paint can grip. Once the surface is ready, it's time to protect the things you don't want to paint. Inside, remove furniture from the room you'll be painting, or move it into the center of the room. Use drop cloths to protect floors and anything else in the room where you'll be painting. You can paint around wall plates, or you can remove them. If you take them down, put them in plastic bags along with the screws that attach them. Finally, read the instructions on the paint can. All paint isn't the same, and the manufacturer knows best what conditions are needed for optimum results.