Always try to pick a warmer, dryer day for this particular task, to avoid leaving the freshly cut stems susceptible to bruising, damage and rot. The object of pruning is to create a structure and shape, suitable to the production of fruit, and healthy growth. When pruning, take a moment to plan the overall growth shape of your plant. Some universal rules are to clear the centre of the canopy, to avoid overcrowding and crossed branches. Try to shape the tree into a vase or wine glass shape. Pick four strong leading branches, and prune to highlight them. Try not to prune more than 30% of a plant at any one time, to avoid shock. It is always good to fertilise plants after a pruning as well, to help them bounce back.