In the winter, prune away approximately 1/3 of the stems of the bush.
Remove the thick, dark stems (these are the ones older than three years, which no longer produce well).
Make your cuts low at the base of the plant, and cut at 45-degree angle, to prevent rot.
Prune away all damaged branches, crossing branches (remove the oldest of the two that are crossing), lateral branches (growing sideways), and branches growing along the ground.
Try to leave 8-12 of the best young upright-growing stems.