When you're working inside with paints, good ventilation is essential. Keep windows and doors open and for extra ventilation, put a fan in the doorway to circulate fresh air from other parts of the house.
Obstacles & Hazards
Take a moment to look around the surrounding area for hazards and instead of painting around obstacles, remove them if you can. You'll get a much neater finish if you even remove handles, locks and so on. Keep all the bits in a plastic bag so you know where they are once you're done.