Using Cheap Paint
If you catch yourself eyeing a discount brand, remember, cheap paint is no bargain. You'll need more of it to cover the same area. And since it won't cover well, you'll have to spend more time to apply extra coats. And after all this, it may not last as long as better quality paint.
Buying a Cheap Roller Cover
We know. You hate cleaning rollers, so you figure you'll just buy a cheap cover and throw it away. Well, guess what? If your time is worth anything, a cheap roller cover is the most expensive tool you can buy. Cheap covers don't hold enough paint, shed fibers on your walls, and in general are a pain to use. We prefer lamb's wool roller covers, but any top-quality roller cover will work fine.
Buying Cheap Masking Tape
Don't scrimp on masking tape. More expensive tape is easier to put on, easier to remove and better at sealing out the paint. There are many specialized types of tape to choose from to suit your task. Some can be left on longer. Some are meant for outdoor use. And others have less aggressive adhesive so you can mask off delicate surfaces. Choose the most appropriate one, but don't buy the cheap stuff.
Using a Low Nap Roller Cover on Walls
A 1/4-in.-nap roller cover is good for applying a smooth finish, but the thin nap doesn't hold much paint. A 3/8- or even 1/2-in.-nap roller cover is best. These thicker covers hold more paint, so it's quicker and easier to apply an even coat of paint. Only buy a 1/4-in.-nap cover if you don't want any stipple on the surface.
Using the Paint From Different Batches
Don't make the mistake of thinking that you can run to the paint store and grab another gallon and it'll be the same exact color. It might be perfect. But there's also a chance it'll be slightly different. If you have to buy more paint, plan to cover an entire wall with the new batch rather than starting where you left off. Slight variations in color or sheen on adjacent walls aren't noticeable
Wiping Too Much Paint from the Brush
The common practice of wiping the brush on the lip of the paint container after dipping it is a bad one. You end up scraping off too much paint. Instead, dip the bristles an inch or two into the paint. Then slap the brush on the side of the paint container to remove excess paint. The brush will be loaded with just the right amount of paint.
Not Buying Enough Paint
We've all done it. The can says a gallon covers 400 sq. ft., and our walls add up to about 800 sq. ft. It seems like 2 gallons should be enough. But in reality, we end up needing two coats, and the paint only covered about 300 sq. ft. on the first coat. So back to the store we go. Remember, the first coat usually requires more paint, especially over bare drywall. And don't forget to add what you'll need for the second coat. Finally, you'll want to have some paint left over for touchup or to repaint a wall later if it gets damaged.
Not Hiring a Pro
One of our Field Editors, David Youngblood, has an idea that's not exactly DIY, but it may be good advice for some people. Hire a good painter. If you don't have the patience to do a good prep job, or will have to buy all kinds of equipment that you may never use again, then it makes sense to at least get an estimate for your paint job. It may not cost as much as you think to have it professionally done. And a poorly done DIY job may end you costing you more in the long run.
Letting Friends Help
'After I selected a very expensive faux-suede paint, two friends eager to see how it looked on the wall came over to help paint. I appreciated the help, but we each had our own technique for applying the paint. We ended up with suede patchwork and had to apply two more coats of paint to fix the problem.'
Using Plastic Drop Cloths
Plastic doesn't make a very good drop cloth underfoot. It doesn't absorb the paint, so any little drip or spill is more likely to get tracked around. Plus, plastic is slippery, increasing the chance of a fall. Four-foot-wide canvas 'runners' are our favorite drop cloths, but old bed sheets, rosin paper or cardboard also work well.