Flat collars are commonly used in clicker training and other non-correction-based training, such as puppy kindergarten. They are also effective in training small dogs, however they tend to lift the dog off the ground when giving corrections while the dog is distracted or in high adrenal mode. They are typically made of nylon or leather, and fasten with a buckle or quick-release connection.
You can start training your dog before they're of age to compete. Begin by working on basic obedience and teach your puppy to sit, lie down, come, heel, and stay. Your puppy will also benefit from attending training classes where they will learn basic obedience and get used to working around lots of other dogs and people. Having your pet take and pass the AKC Good Citizen Test is a helpful step.
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.
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.