Prep the area

Before you can start painting the wall, you have to clean it. Make sure the surface is free of any dirt, smudges, or stains. First, you should use a damp sponge or magic sponge. Then dry it with a clean towel. Repeat as necessary until there isn’t any grease, dirt, or grime on the wall. Using a spackle compound you can fill any holes, dings, or gashes in the wall. First, you’ll want to sand it down any rough areas with 120 grit sandpaper and wipe it off with a wet paper towel to get off the dust. Scoop the spackle out with a putty knife and smear it into the hole until it is full. Let the spackle dry and sand down with fine-grit sandpaper to make it flush with the wall. Clean off the dust with a damp towel and you’re done.

Primer

If you use a thin coat of primer on the spot you touching up it can help blend it and increase paint adhesion. With a small brush apply a light coat of the primer making sure to not go too far beyond the spot you’re touching up.

Get the paint ready

Before you can paint you should thoroughly shake and mix the paint, either with a sticker or a power drill mixer if you have one. One thing you should consider to make the touchup blend into the wall better is to thin it. Adding water to latex or turpentine to oil-based paint can make the transion smoother and the paint easier to apply. The paint should have proper instructions on the label on what to use and how much you should use.

Paint

Once your paint is ready you can load your brush or roller with paint and begin. You’ll want to start in the middle working your way out to spread the paint. Once you get to the edge of your spot make short strokes pushing the paint out to create a feathered effect and blend the paint. This will create a much less noticeable transition allowing the touchup to blend into the wall. A foam brush is recommended for spots under an inch.