Collar conditioning is very important when using E-collar's for training. The dog needs to understand what the shock is for, and why he/she is being shocked. Most of the Yard systems have a very good description of how to do this in their directions.
If you're using an Ecollar for other training, the dog needs to understand the command before you start using the shock collar. Ecollar's help expand your ability to handle a dog, but the dog must understand the command off of leash first with the Ecollar slowly being introduced.
V's can be very soft dogs, and training should be catered to the individual dog.