Martingale collars (also called limited-slip collars) are usually made of flat nylon with a smaller fixed-length section (made of either nylon or a short length of chain) that, when pulled on by the leash, shortens up tightening the collar around the dog's neck, to a limited extent. When properly fitted, martingales are looser than flat-buckle collars when not tightened, and less severely corrective than slip collars when tightened.
Basic or beginner's obedience is typically a short course ranging from six to ten weeks, where it is demonstrated to the handler how to communicate with and train the dog in a few simple commands. With most methods the dog is trained one command at a time. Though there may or may not be a specific word attached to it, walking properly on a leash, or leash control, is often the first training required prior to learning other commands.
Most training schools are happy to allow you to attend and observe (leave Fido at home for this) a class or two to be sure the style of instruction fits with your beliefs. Dogs learn best through progressive reinforcement training; rewarding the dog for making the right choice and withholding rewards, or ignoring the dog for making an incorrect choice.
Head halters are an alternative to collars that works similarly to a horse halter. The halter fits over the dog's snout and behind its head (leading it to sometimes be mistaken for a muzzle). Halters reduce the dog's ability to successfully pull on the leash, but do not eliminate it. If the halter is used with a sharp jerk on the leash, neck injury to the dog may result, but used correctly head halters have not been shown to cause harm.
Every dog needs to learn to walk on a leash. Besides the fact that most areas have leash laws, there will be times when keeping your dog on a leash is for his own safety. Learn how to introduce your dog or puppy to the leash, then teach him how to walk properly on the leash, even beside you on a bike. A loose leash walk teaches your dog not to pull or lunge when on the leash, making the experience more enjoyable for both you and your dog.