Building painting contractors follow a systematic approach to ensure a durable and long-lasting paint job. They begin by thoroughly preparing the surfaces, which involves cleaning, sanding, and repairing any imperfections. Contractors also use high-quality primers and paint products that are specifically formulated for different surfaces and conditions. Proper application techniques, such as brush, roller, or spray, are employed to achieve a smooth and even coat. Lastly, contractors may apply protective coatings or sealants to enhance the durability and longevity of the paint.