Scrape off any chipped or peeling paint using a paint scraper or a putty knife. Sand any rough spots on the wood using sandpaper.
Mix two to three drops of liquid dish soap with warm water in a bucket. Scrub the porch using the soapy water and a sponge or cloth. Let the porch air dry.
Paint the porch with a primer. Select the primer based on the age and condition of your wood.
Stir the paint with a paint stirrer until all of the oils from the top are mixed in thoroughly. Pour one inch of paint into a roller tray covered with a liner.
Paint the porch, starting with the farthest corners and working toward your exit. Paint larger areas with a paint roller, and smaller, more detailed areas with a paintbrush. Cover the entire porch with a thin coat of paint and let it air dry.
Look at the porch carefully once the paint has dried. If any streaks or brush strokes are obvious, or if you can see through the paint in any place, another coat will be necessary.