1. Don't prune more than you need to. 2. Prune when the tree is not actively growing. So winter would be best. 3. Remember when one is pruning that the reason that we prune is to encourage new growth and to get rid of dead wood. 4. Cut back to create the right shape for your garden. If you need to screen an ugly wall then keep the plant at the correct height and let it become bushy. 5. Utilize the branches that you have cut off by cutting them into short lengths and using them as mulch under the tree. They will eventually break down into compost.