Cut out any obviously dead or damaged branches first. Then cut out all but four or five healthy stems, each ideally about as thick as a pencil. Make these cuts right above an outward facing bud - that is, a red bud that's on the outside of the rose bush. This directs the bud to grow up and out, leaving the center of the rose bush open for a prettier shape and better air circulation. Fertilize roses regularly during the growing season.
Roses are hungry plants, demanding lots of nutrients for best growth and flowering.
Each rose grower has his or her own favorite method. One of the easiest is to buy a slow-release granular rose food and work it into the soil so it can feed the plant all season long. Roses need a steady source of water during the growing season, about 1 inch a week from rain or watering. If your rose is a climbing or rambling rose, prune with caution. Some will bloom only on old wood from the previous year.