Make your new or older home look elegant by installing crown moldings.  If you have cracks where the wall meets the ceiling this is a quick permanent fix. First step is to pick the molding. The easiest to install is a flat molding (see picture below). If there are cracks seal them with a good caulk. Try to keep the caulk seam flat so the molding will fit snug against the wall and ceiling. Measure how much molding you need. Moldings come in 8 and 16 foot lengths, the later being hard to transport from the store. I recommend that you paint the moldings with the color you want before cutting and hanging them. That way you only need to fill and paint the nail holes. If the corners don’t come out perfect use some Patch & Paint spackling past to fill in and sand and paint when dry. You will need a miter box or miter saw for the 45 degree cuts.  Measure twice before you cut. The next part you need 2 people to position and nail up the molding. You can put a thin layer of joint compound on the back of the molding before hanging. Use 2” finish nails or a nail gun to put up the molding. Below is a picture of my 33 year old living room after I put up crown moldings.