Prepare a solution of water and powered detergent. Rinse off the awning with a hose.
Wipe off any dirt or debris with a wet sponge or cloth. Scrub the awning with a scrub brush. Rinse the awning with clear water.
Prepare a solution of 1 part bleach to 3 parts water in a bucket. Spray the solution onto the awning, or scrub the solution onto the awning with a sponge. The bleach is to remove any mold or mildew.
Sand off any areas on your awning that are flaky or feel rough to the touch after the awning is completely dry. Sand the awning until the metal is shiny and smooth. Brush off any remaining debris from the sanding.
Place painter's tape or another protective material to block off any areas where you want to avoid splattering paint.
Place a primer on the aluminum awning. The primer should be a metal-priming paint that is thinned down and oil based.
Paint the awning with acrylic latex exterior house paint within 48 hours of applying the primer.