Stick with quality brushes. They cost a bit more, but they are worth it in the long run. Clean them after each use and they will last a long long time. You will need a 2 or 2 ½ inch angular sash brush and the same size trim brush. Choose a premium brush with long dense flagged bristles. (Flagged bristles are not square cut but are split on the ends). These brushes will hold more paint and drip less.
Use a synthetic brush when painting with latex paints. Although synthetic brushes can be used with Alkyd
paints, I prefer a natural bristle brush.
Make sure the brush holds the bristles tightly. (nothing is worse than a shedding brush)
You will want brushes for cutting in and painting in areas that your roller can't reach. Foam brushes may have their uses, but interior wall painting is not one.
On large flat surfaces rollers work best. You can even buy rollers that are fed from the can via a small pump, however I prefer a simple tray.
Rollers should be chosen based on the the texture of the surface and the type of paint you are applying.
Eggshells..............3/8" nap (longer)
Alkyds..................3/16" nap (shorter)
Higher glosses use a shorter nap
smooth...................1/8 – 3/8
semi-smooth..........3/8 – ½
semi- rough............½ - ¾
rough......................¾ - 1 ¼
The fundamental difference is the glue used to hold the paint together. Exterior paint glue is more soft and flexible to resist heat and moisture. Interior paint glue is harder which makes it washable.
Many stains, paints, and clear finishes have a limited shelf life. It's a good idea to label a half-empty can with the current date. Next time you need to use the finish, you will have a written record of how long it's been sitting on the shelf.