Most dog behavior problems can be prevented or fixed with Management. Good management makes training good behavior easy.
An Ounce of Prevention...
How do you keep toddlers from sticking a fork in an electrical socket, eating poisonous chemicals, playing with knives, or running into traffic while you shower or sleep? The answer is management. Fasten covers on the outlets, cabinet locks where chemicals are stored, drawer locks where knives are kept, and doors locked.
Dog intelligence is similar to that of a 2 - 2.5 year old human. No rational adult would sit a 2 year old child in the middle of the kitchen floor and say "be good" while they go run an errand. They would not assume the child was being "spiteful" if they did something "wrong", understanding that children act out of curiousity and impulse at that age and are largely self-absorbed. Leaving an untrained dog home alone with free run is like leaving a 14 year old child home alone with an unlocked liquor cabinet and keys to the sports car. It's asking for trouble!
The longer a behavior is practiced, the more it becomes habit. Habits literally form pathways in the brain, the same way a path is worn in the grass over time. Unwanted behavior is basically a bad habit. It is much easier to prevent a habit from starting than to break one after it starts. A person who has never smoked a cigarette will have a much easier time with a work-sponsored no smoking challenge than a person who has smoked 2 packs a day for years. A dog who has never counter surfed will be much easier to keep off the counters than one who has done it countless times and scored some delicious food in the process. A dog who has never jumped on a person will be much easier to keep off of people than one who has jumped repeatedly for months or years. If you have ever tried to break a bad habit, you understand the feeling. Even when you WANT to stop, biology is fighting against you. The pathway is formed, and it takes time for the grass to regrow and cover it.
A Pound of Cure
If your dog already has bad habits, management is the first step is breaking them. A dieter would not be successful if their favorite dessert was sitting in front of them day after day with a note that reads "eat me". Sooner or later, they are going to cave. Put away the cheesecake to set your dog up for success. Management will be needed longer for breaking an established habit than for preventing one.
How to use Management
The simplest way to use management is to crate train. It's hard to account for every single thing a bored or curious dog could get into. I once left a dog in a completely empty room with nothing but chew toys, and she ate the door molding and baseboards. So, I left her in the living room thinking she would be happier there. She climbed a shelf and ate a bottle of tylenol. After having her stomach pumped, I bought a crate. She needed it until she was 2 years old. Other dogs only needed it a few months, and still others only a few weeks. Every dog is different and matures at their own pace. Click here for a guide to crate training.
Other management tools include baby gates, cabinet locks, x-pens, window film, and tethers. A dog cannot bolt out of the front door if they are behind a baby gate. They cannot dig in the trash if the trash can is out of reach. They can't bark non-stop at passersby if they can't see out the window. They can't jump on visitors if they can't reach the visitor. They can't counter surf if they can't get to the counter.
How to fade Management
Management in most cases can eventually be faded out, like the socket covers can be removed when the toddler is older. Either the dog matures to the stage where he no longer is getting into everything or he learns a better behavior. Training speeds up the process. Teach the dog to Sit to greet people, and they will not need to be tethered when guests come over. Teach them to chew only on their toys and use the bathroom only outside, and they won't need to be crated when not supervised. Teach them that good things come from the floor and not counters, and they won't have to be kept out of the kitchen. Continue using management until you would put $100 down and bet that your dog will not need it.
Some things may have to be managed forever. Behaviors that are hard-wired and normal for dogs are impossible (and arguably unethical) to "train out". Dogs have certain genetic traits that are "dog". They have fur (or are hairless) and not feathers or scales. They walk on 4 legs and not 2, and they don't have wings. They bark and don't purr or whistle. They are omnivores and not vegans. Some things that are "dog" are unsavory to humans, like rolling in dead things, killing small animals, and eating cat poop. Some traits have been selected for by humans for thousands of years such as herding and guarding. These traits can be directed but not trained away any more than a dog can be taught to quack instead of bark. It's something to consider when choosing a dog. If the thought of being gifted with a dead baby rabbit or bird makes you squeamish, a terrier would not be a good choice. Herding breeds will likely herd the children. Shelties and Pomeranians bark loudly and often.