[header] How to paint concrete [title] Clean the concrete surface with soap and warm water, removing any old paint. [step] First, sweep away any surface leaves, debris, and dirt. Then remove any existing paint or gunk using a power washer or scraper and wire brush. 
Scrub away any dirt, grime, or gunk that is stuck to the concrete. You do not have to worry about stains, however, if they are set in and not some sort of object stuck onto the surface.