Start by cutting in paint around the edges of the wall with a brush first, and then fill in the larger areas with a roller. This will keep paint off the ceiling and baseboards. New roller naps often have loose fibers. Avoid fibers sticking to the wall by wrapping the entire roller nap with masking tape. Then just pull it off, loose fibers and all.
Many people are sensitive to paint odors.
You can cut down on them by mixing half a small bottle of vanilla extract into the paint. It will make the odor less intense without affecting the color or quality of the paint. Once you finish painting, secure the lid and store the can upside down. This will help prevent a film from forming on the paint's surface. It's also a good idea to brush a bit of paint on the outside of the can to indicate how much paint is left.