Skipping prep time
“Lack of proper prep is usually the biggest difference between DIY and professional projects,” says Tom Lee, Senior VP of Consumer Marketing for Behr. “Homeowners understandably want to jump right into the project, because they’re excited to see their new color on their walls — it’s an emotional reaction. But keep in mind that professional painters spend the majority of their time on prep.” Make sure you’ve properly cleaned walls, scraped off peels and cracks, applied painter’s tape carefully, and allowed any patching compound to dry before you start.
Going without primer
Primer covers flaws in the surface and gives you a smooth, long-lasting finish. It’s fine to use paint-and-primer-in-one mixes if the old surface was previously painted, is in good shape, and has a flat (non-glossy) finish. But if you’re painting over a more difficult surface such as plaster, wood, concrete, glossy paint, or stained/porous drywall, use a stand-alone primer or a premium all-in-one mix specifically designed to cover unpainted surfaces.
Painting over high-gloss paint without sanding
New paint needs some texture to adhere to, so make sure to lightly scuff any shiny surfaces with sandpaper, followed by a rinse with clean water.