Repair a wall...

Before you paint any wall you must repair any cracks and fill all holes. When repairing a crack it is very important to remove all loose paint. Be aware that a small crack can easily become a larger blemish once you remove all the loose paint. Don't panic! You are doing the right thing for a permanent repair. Once the loose paint is gone, wipe down the area with a dry cloth. Now prepare the surface for spackling. If crack is larger than 1/4'' or if you can fit two nickels side by side, than you should use some joint paper or mesh to retain the plaster and to prevent the crack from coming back. If the the crack is not that bad, simply fill it first and then proceed to plaster the bare spot. I found this great spackle at ACE Hardware, it is a vinylized spackle. It is not two heavy so it won't droop, yet it is thick enough to go on smoothly. The benefit of this type of spackle is that the vinyl helps it not only to adhere better, but it also helps to prevent a new crack. Remember to take your time. Several light coats are far better than one heavy one. When you do light coats you will be able to control the finished product better and with little sanding. Remember to wait between coats to dry. Once you are done and you prime the area or use one of those new paints with primer already included, you will be the only one that knows that wall was ever damaged. Sit back and enjoy the fruit of your labor.