Following the same process as the primer, cut in the walls with your chosen paint. For best results, paint one wall at a time. This makes it easier to spread the paint while it’s still wet. Work from top to bottom, rolling the paint in V or W-shaped strokes. Before applying a second coat, wait two to four hours. Then proceed with the same process used for the first coat.
It's up to you. Outside is much harder because it requires more prep, patience, time, help, money and of course, effort. I have been painting my own houses and rental properties interiors for 20 years, and I painted the exterior of one, once. I then had it promptly done again by professionals who said it would have been cheaper if they didn't have to undo my work first. My advice is to get pros for the outside because everyone will see it.
Expect to pay between $600 to $3,500 or $1.25 to $3 per square foot to coat vinyl, with prices likely increasing for the finish. It is one of the more inexpensive siding materials to have repainted, especially with recent innovations in materials. Changing the finish on your siding is not recommended unless it's completely degraded and worn away by the weather. You can save nearly half the vinyl siding installation cost of $4 per square foot by painting rather than replacing. Before adding a new coat to vinyl siding,