Here is the "battle kit" Leo assembled for a flawless finish: 1. The Surface Prep (Don't skip this!)

Unless you want to spend the day climbing up and down a ladder, this is a literal lifesaver for your back.

Get a "3/8-inch nap" for standard smooth walls. If your walls are textured, go for a thicker nap.

Especially if you are painting a light color over a dark one, or painting fresh drywall.