"For maximum fruiting, it is best to train plants against a wall or fence, tying the lax stems onto wires. Wear gloves for protection against spines.

Flowers and fruit are formed on the stems that grew in the previous year, so pruning aims to encourage the production of this wood.

Prune lightly in early spring, removing dead and badly-placed shoots. If necessary, cut overlong stems back to a well-placed branch and remove some of the oldest wood
Renovate shrubs in early spring, reducing the plant to a low framework of branches or cutting close to the base. This will cause vigorous re-growth, but initially reduces the fruiting
To restrict growth on plants in containers, cut new growth back by up to half in summer (however, this will reduce the yield)"

From RHS in the UK. In case you never got a reply to this old post.