This job is usually done by a professional house painter. The painter will assess the walls, clean, and make any necessary repairs or removal of old wall coverings. They will also tape off any adjacent surfaces and cover nearby furniture and floors with drop cloths. Typically, they will apply a layer of primer, then one to three coats of paint, depending on the color and coverage. Once the paint is dry, they take a final walkthrough to inspect and make any necessary touch ups.
A professional paint crew will have the right tools for the job. Quality tools can make a difference in paint application and bear noticeable results. If you are only painting one room or do not plan to paint any additional areas of your home, it might not be wise to invest in tools that will only be used once. Professional painters will also have enough drop cloths and other protective equipment to ensure the area is kept clean.
The right paint stroke to use in interior painting is highly debatable. It's not a talent as much as a skill that is learned through practice. Many experts paint in a “W” pattern when using foam rollers, but others simply roll up and down then sideways with either brushes or rollers. The motion isn’t as important as making sure that the application is even and drip-free across the entire area. However, technique is important when you're covering over wall repairs.