Spike Carlsen: You want to make sure that your walls are clean so the paint will stick to them. The best way to clean walls is with TSP or a TSP substitute, rinse them and then make sure they are dry. On most walls you are going to find little dings and dents. Major leak holes like this need a little bit of reinforcement.
So what we have here is self-sticking fiberglass tape, put it over the hole and then give it a coat of dry wall compound. It's probably going to take you a few coats. When you wind up little holes like this where pictures were hung, lots of times, you don't really have holes as much as you have a dimple and if you just put dry wall compound over that, you just wind up with a bigger dimple.
So the solution to that is to take a hammer, give it a couple big taps to make it indented and then put your dry wall compound over there. Again, it may take a couple coats to get the surface perfectly smooth.
Once you have patched your dings and dents and you have let them dry, you just want to go ahead and you just slightly feather the edges so that they blend in. Then you give them a coat of primer and then those are ready for paint.
Another situation, you might run into is flaky paint, as you go around your room take a look at that. If your house has built prior to 1978 then it's a good chance you have lead paint in it, in that case don't sand it, simply prime it and go over it.
If you have a newer house and flaky paint, use your sanding block to soften and feather those edges, prime them and then those would be ready for paint.