Brushes with square-cornered ferrules are narrow and don't hold as much paint as those with rounded corners, making them good to use on small surfaces.
Ferrules with round corners allow the brush to hold a good amount of paint when the job calls for both cutting lines and spreading paint quickly.
A brush with a large oval-shaped ferrule holds the most paint and is useful for painting large areas that might require some cutting but don't require any precision cuts.
When a brush is dipped in paint, one-half to two-thirds of the bristle length should be wet. Tapping the brush against the side of the can rids it of excessive paint.
A Handy Pail has disposable liners and a magnet that keeps a brush suspended in paint when it's not being used.