Here are some steps to follow if you are contemplating your own home paint job:
First of all, if you are going to be using more than one can of paint, mix several together or parts of them in order to guarantee color consistency. Each can is mixed at the store separately, so the chances of each can being exact are not probable. This is a good rule to follow.
Paint needs a clean, smooth surface for the strongest bond to take place. Take the time to mildly scrub the walls, you won't regret this.
Holes in the drywall need to be filled with a strong filler. Ask your dealer for a product that's best, probably something like Durabond. Most water damaged areas need to be replaced; this can be tricky for the inexperienced. But if you are tackling it, cut the smallest area you can up to the stud in behind, fasten a slat behind the drywall stud to stud to hold the drywall piece firmly in place. Then fill and smooth.
Move all furniture to middle of room and cover entirely with preferably cotton drop cloths, we feel cotton is better than plastic for clean-up.
Priming is not always required although you most likely use less final coat paint, especially when painting light colors over darker ones. Test a small area until you are happy.
Trim first, ceilings next, then finally the walls. Doing this order will make taping easier, just doing it once.
Paint tends to dry out if the lid is off for a time. For this reason use a smaller container and refill it as needed. The pros roll the full height of any wall to keep lap over marks from occurring, do the same; and don't let the roller edge get dry. Use the roller to paint outward edges (corners) for smoothness.
Tape your trim edges where walls and ceilings meet. 1/2" tape should do it. You need a steady hand to paint where wall meets ceiling, tape can peel a finish off of a painted surface. Some folks use a sharp edge to protect the adjoining surface.
Remove tape after some drying has happened so no bleeding occurs. Wait too long and it may crack where paint has dried.