It is essential to follow through on a backhand. By pointing the point of your stick for a follow through, you will increase your accuracy and it will give you more snap in your wrists providing you with more power.
Hand positioning is important for a backhand. If your hands are too close together, you will have less control and less power. If they are too far apart, you will have less control and will probably end up shooting the puck over the net. Ideally, you want to keep your hands a comfortable length apart and maybe even lower your bottom hand a little to increase your control.