Clean Fast with TSP
You have to start with a clean surface for paint to adhere to previously painted walls and woodwork. Use a sponge and a trisodium phosphate cleaner (or TSP substitute) to quickly wash off dirt, grime and soot. TSP cleans fast and usually doesn't require a lot of scrubbing. Buy TSP concentrate and mix it with water—it's a better value than liquid TSP. A 16-oz. box costs about $5 at home centers.
Use TSP on all of your woodwork. It slightly etches the paint, which helps the paint form a better bond. And use it in kitchens to clean grease from walls, in bathrooms to remove hairspray and around light switches to remove fingerprints. Wear rubber gloves and turn up the cuffs to keep the TSP solution from running down your arm.
Strain Out the Goobers
Even if you open your paint right after bringing it home from the paint store, you can still have small chunks or strands of hard paint in it. If those end up on the wall, you'll have to pick them out and reroll the area. So spend two minutes straining out the goobers.
Buy a paint strainer at a home center or paint store or use old pantyhose to strain the paint. Place the strainer over a 5-gallon bucket, then pour the paint through the strainer. The strainer catches any debris in the paint. If you really want to be dollar savvy, rinse out the strainer in the sink and reuse it.
Paint Window Sashes Faster
Most DIYers slop paint onto the glass when painting windows, then scrape it off with a razor. But if you're good with a paintbrush, you can cut in along the glass. You won't have to scrape, and better yet, you'll leave the paint seal intact between the wood and the glass.
Load your brush and lay off the paint on the sash, staying about 1/2 in. from the glass. As soon as the brush is about half unloaded, go back and cut in closely. Let the brush bristles just barely touch the glass so the paint seals the tiny gap between the wood and the glass. If paint does drip on the window, scrape it off with a razor after it dries.