Painting companies are very easy to market actually. You put your name in multiple places. Slap it on the side of your truck, pass out fliers, post Craigslist listings in your local area, etc. You can also go additional routes such as website/SEO (Search Engine Optimization *GOOGLE*) and put your listings in Yellowpages or even online yellowpages (Which tend to be on the better priced side compared to phone books)
what is your challenge. lol.
