Generous and proper pruning creates bigger plants and eventually more flowers per plant. Selective pruning of top growth can produce bigger, but fewer, blooms. Don't be nervous about pruning - there is no evidence that anyone ever killed a plant with pruning shears!
In general, most roses should be pruned in early spring just before new red growth emerges. This ensures that the rose will have a good habit and healthy blooms throughout the season.
Old-fashioned roses and climbers that bloom only once a year should be pruned immediately after flowering since they bloom on wood from the previous year's growth.
To prune roses you'll need sharp curved-edge pruning shears, long-handled lopping shears and leather gardening gloves. In general, all roses should be pruned by making cuts at a 45º angle.
Pick 4-6 sturdy, healthy green branches that form a nice vase shape. These branches should be open in the center with no crossing. These will be the only remaining branches when you have completed all of your pruning. If you are pruning landscape shrub roses, you really don't need to follow the next steps. You can simply prune or shear the shrub down to about 1/3 or 1/2 it's current height.
Deadwood is usually blackened and most often will break away easily if pulled. Cut at the base, making sure not to damage the bud union.
Prune canes at the base, making sure not to cut into the bud union.
Prune away any canes that cross or rub against each other. Cut at the base, making sure not to damage the bud union. This will promote good air circulation and will help prevent disease and pests.
Shorten the 4-6 remaining healthy canes to 1 to 4 feet, depending on the mature height of the rose and your personal preferences. Generally, this reduces the height of the plant by 1/3 to 1/2.
Below each spent blossom, prune just above the first set of 5 leaflets. This will encourage another round of flowers.