Use frog tape to tape plastic down and edges. Remove light switch covers and outlet covers (tape over the moving parts and holes). Use and edging tool first and multiple thin coats are better than fewer thick coats.

Get sample colors and paint small sections on the walls. Watch for 24 hours to see the color in all lights. If the horrible color bleeds through, do a layer of primer first, or get a paint with primer built in. Use a high quality roller and remove lint by wrapping masking tape sticky side down around it.

When you are painting, be barefoot (easier to know you stepped in something)