Identify your starting point. If you favor your right hand you should begin where the walls meet the woodwork or the ceiling in the top portion of the right-hand corner of the room. Lefties should begin painting in the top portion of the left-hand corner of the room.
Dip a 2-inch paintbrush into the wall paint. Do not overload your brush with paint. Wet the bottom half of the bristles and then tap the bristles against the side of the container to remove excess paint. Resist the temptation to wipe the brush against the rim of the container as this creates bubbles in the paint.
Hold your paintbrush at a 45-degree angle and apply a 6-inch long strip of paint to the wall along the ceiling or molding edges. Work from the top of the room to the bottom of the room. Apply another strip of paint, slightly overlapping the first. This keeps a "wet edge" to your paint. Apply paint in this manner to create a 4-inch band of paint all around the edges of the room. Blot paint spills with a paper towel as you work.
Take advantage of a stepladder. Working from a stepladder provides additional support while you control your brush and helps to reduce back strain. Continue edging the walls of the entire room without stopping. You create a noticeable "hesitation mark" whenever you stop painting and resume at a later time.