If you have kids or pets sooner or later you'll need to touch up your interior paint. Once you learn a few professional touch-up tricks, your walls will always look great.
Patch any holes. Simply fill in the hole with spackle or putty and scrape the surface until its level with your wall. If the hole in your wall is larger than 1/2 inch, you will need to buy a patching kit at your home improvement store. Most patching kits involve gluing a piece of mesh over the hole and then smoothing spackle over the mesh.
Sand any area you have patched. Sand your patched areas and make them smooth against your wall. If you wall has a texture, you will need to match that texture using your spackle or putty. Many tract homes have a splattered surface. There's only one way to imitate that--do some splattering yourself. Flick small amounts of spackle on your repaired area until it looks similar to the texture on the entire wall.
Paint your repaired area with matching paint. Allow paint to dry for at least 24 hours.
When your paint is thoroughly dry, sand your repair and the area surrounding it with fine sandpaper. This will dull the area.
Paint your repaired area one more time. Painting over the sanded area should cause the repair to fade into the surrounding wall and not be noticeable.
Keep a small jar of your interior paint easily accessible for quick touch-ups.
If an area is a constantly in need of touching up, consider changing your wall treatment to something more durable like certain wallpapers or wainscoting.