Cheap paint
You should always use quality paint, and the truth is, you get what your pay for. Cheaper paint may look fine when you are painting it onto the walls, but when it dries, you will see the difference. High quality paint is also easier to apply and will last longer. The same goes for brushes and rollers. The better the quality, the better the result.
Overloading the paint roller or brush
If you think you’ll save time – or only need one coat -by slathering on a thick coat of paint, you’re wrong! A thick coat of paint will run and take a long time to dry so applying two thin, even coats will give you much better results.
Not preparing the surface
You can’t just start painting with no preparation. Areas to be painted need to be clean, dry and smooth. If you paint over an imperfection, it will still be there when the paint dries. And no, paint won’t fill cracks or gaps! They need to be repaired properly before you start.
Impatience!
Starting your second coat before the first is dry is a big mistake. The worst-case scenario is that your first coat will start to come off onto your brush or roller and cause a real mess. Always follow the drying time instructions on the paint can.