To help your tree maintain shape and style it is necessary to cut the branches back at certain times of the year. The idea of cutting back is to maintain horizontal branching with 'pads' of leaves to imitate mature trees with heavy solid branches being pulled down by the weight of the leaves. Regular and correct branch cutting also reduces the size of the leaf. There will be times between these cuttings that your tree will have that "shaggy dog" appearance.

Don't panic and cut the branches too early or at the wrong time. A little patience is all that is required to have a beautiful plant that should last a lifetime.

When the new shoots have 'set' its time to cut them back. When the shoots first grow they are green, as they get older they appear more woody, it is when they look woody that they are 'set'. Some trees can be cut back twice a year and others only once. See the individual instructions for your tree to establish branch cutting times.

The shoot should be cut above the leaf from where you want the new shoot to grow. Remember that you want outward growing horizontal branches. Cut this shoot back to the first, second or third leaf of the new growth depending on which direction you want the new branch to grow. Don't worry if you make a mistake, the tree will continually grow, and most mistakes will grow better.

Very Nice advice on this subject Dex,

Also once become good at this i believe you can almost know your bonsai so well that even cutting/trimming certain spots the bonsai plant will grow its look and design the way you want, this is what brings enthusiasts so addicted to there work.