Choose the proper time for pruning. You are going to want to prune your rose bush early in the spring, after the last snowfall but before any new growth. A good indicator that you have chosen the right time is to look for swelling in the buds. When the buds have just begun to swell, to roughly the size of a sunflower seed, it is time for pruning.
Select the proper tools for the job. When dealing with thinner branches -- roughly half an inch in diameter or less -- a pair of pruning shears will work just fine. When dealing with thicker branches, use a lopper to get that bit of added leverage. Also, don't forget to wear proper hand and eye protection, as those thorns can be quite prickly.
Look for any dead branches first. The dead wood will have turned black all the way through, whereas healthy will be white in the center and green on the outside. Cut away any dead branches you find as close to the base as possible.
Trim out any limbs that appear to be thinner or more spindly than the average. Generally these branches will be thinner than a pencil, but this can vary depending on how healthy and vigorous the overall rosebush is.
Look for branches that cross other branches or which rub against other limbs. These can quickly become problem areas for disease and decay, so it is best to remove them. This will also help open up the rosebush, giving it a more pleasing look.
Continue cutting back limbs to create a vase or fountain shape. The goal is to have five to eight sturdy, healthy, upright branches serving as the core of the rosebush with an opening in the center portion of the bush and no crossing limbs.
Trim back the healthy branches to between 2 and 4 feet in height, depending on the mature height of the rosebush. As a general rule, cut the rosebush back to a height equal to half the height you would like to see it grow to once it matures. When making these cuts, be sure to cut the branch at a forty-five degree angle from the ground and cut just above one of the outward facing bulbs on the limb. This will help to encourage new growth and proper circulation for your rosebush.