What is the best way to prune rose bushes ?

Answer 1

"The way you cut your roses can affect the health of your roses. Taking long stems with the flowers, weakens the plants because of the loss of foliage. The general rule to follow when removing roses is to cut just above the first leaf with five leaflets. New plants are especially sensitive to leaf loss, so take only short stems along with the blooms during the first year."
http://www.ext.nodak.edu/county/cass/horticulture/inform/flowers/cut.htm

For more established plants with a lot of foliage, cutting longer stems with the flower isn't a problem. "You can cut them down to where they originate at the previous stem if you wish. You can also cut any stems that are in the way of walkways or otherwise creating a problem. As the roses go dormant and flowering ceases, you can cut extremely long canes of hybrid tea, grandiflora, and floribunda roses back to prevent them from whipping around in the wind and damaging the plant..."
http://www.cahe.nmsu.edu/ces/yard/1996/093096.html
The type of rose determines how & when you prune it. Hybrid Teas, Floribundas & Grandifloras are usually pruned in the early spring. The Ramblers flowers are formed on year old canes, which should be cut back to within 2-3 inches of their base when they are finished blooming. Climbers don't like hard pruning & should be trimed only lightly in early spring. Miniature roses need very little pruning. Just prune them to the desired shape. Cut any new shoots which have emerged from below the soil line to about 1/2 its length. When the branches finish flowering, cut them back to a new outward facing bud.
http://www.thegardenhelper.com/pruningroses.htm
Good luck with your roses! Hope this helps.