What defines a pet beagle from a smelly dog in the alley is how it acts around people. Dogs without training, mostly street dogs, are very elusive. Sometimes they can be very aggressive for no reason. This is why pets should go through proper dog obedience training. Since your pet dog is going to be around people a lot, might as well play it safe and teach it some manners.
Let's start at the beginning.
Socializing your pet
Dog obedience training begins at the early stages of a dog's life, as a pup. This is the most appropriate time to teach your dog all the basic commands it needs as an adult. It is possible to start teaching dog obedience training to an older dog, if you missed the opportunity when it was still a pup, but it's going to be twice as hard so be prepared for that.
Normally a pup learns to socialize through its mother and siblings. But if your pet puppy was separated from its mother at birth, which is likely the case, you need to find ways to let it socialize with other animals. Take it outside for a walk every now and then, and let it mingle with other puppies and dogs in the neighborhood. Puppies who skip this period tend to grow up estranged and detached from people and other animals.
Pet dogs don't bite
It's almost as if it is an uncontrollable urge for them. Little puppies will chew on anything and everything. Your carpet, your drapes, your children's toys, your new sandals. You need to put a stop to this filthy mannerism before it makes its way into your dog's adult habits.
The thing is to put away everything that could fit in the puppies small mouth. Keep all of it out of reach. Reprimand your puppy if necessary; by this time it should be able to perceive if the difference between punishment and praise.
The clicker
The clicker is a hand-held clicking device used in conjunction with a type of dog obedience training called the “clicker training”. It is an established method of teaching pets and guard dogs some basic commands like sit, fetch, run, quiet, etc.
"Is a clicker really necessary?" you ask. A clicker makes it easier to associate something to a particular deed or action, but it isn't necessary. It's possible to teach your dog the basic commands without using a clicker. It's going to be a lot more difficult for both of you though—you and the dog—since the clicker is supposed to produce this unique clicking sound that doesn't get easily drowned out by other noises.
This article (link to Guard Dog Training) has more detailed information about clicker training.
Good luck on your dog obedience training. We wish you and your dog all the best.