Sand, Sand And Sand Some More

Any surface you are going to paint on has got to be flat. It literally cannot be flat enough. The slightest ripple or texture can cause an annoying seam that will nag at you. When you think you've sanded enough, sand it once more. Then completely inspect it, make sure all dust is removed, apply a coat, wait and inspect before proceeding.

Cleanliness is key

A clean, organized work area is mandatory when painting. Spilled drinks or smudges can destroy all of your hard work, loose garbage can blow into a wall, and the last thing that you want is to get moisture or dirt between the wall and the paint you just spent all of that time sanding.

Buy More Than You Need

Buy enough to allow for mistakes and for touch-ups in the future. A new coat of paint can be marked or nicked accidentally, and you might not find the same mixture at a later date if the hardware store doesn't carry or make it anymore.

Tape and cover properly

Tape can save you from making annoying, time consuming, and even costly mistakes. Tape all corners and seems, sills, anything where you want a crisp even line. That way when your brush goes out of bounds, you don't get a smudge; and when you remove the tape, your line will be perfect. Use a tarp over the entire room to prevent paint spills and splatters on your furniture and floors.