Prong collars must never be turned inside out (with the prongs facing away from the dog's skin), as this may cause injury against the body and head.  Plastic tips are occasionally placed on the ends of the prongs to protect against tufts forming in the fur or, in the case of low quality manufactured collars with rough chisel cut ends, puncturing the skin. Like the slip collar, the prong collar is placed high on the dog's neck, just behind the ears, at the most sensitive point.
The clicker is a small hand-held device that makes a distinct, short sound to mark a desired behavior. (See clicker training for a more detailed discussion of this methodology.) It has gained popularity in recent years as being a means of training that does not involve physically correcting the dog, though it may be used in conjunction with these methods.
RutRoh is an English Sheep Dog, born Deaf. He is a wonderful dog and family companion, however, being deaf and living in Dallas, his safety was one of the reason he was brought to us for training. His owners didn't want to have restrict him to be on a leash all the time. They wanted him to be able to run and play and have a way to communicate with him when he was not in view of them.
Remember that training is an ongoing process. You will never be completely finished. It is important to keep working on obedience training throughout the life of your dog. People who learn a language at a young age but stop speaking that language may forget much of it as they grow older. The same goes for your dog: use it or lose it. Running through even the most basic tricks and commands will help them stay fresh in your dog's mind. Plus, it's a great way to spend time with your dog.