First, if your dog barks because it is bored, it needs some exercise. Many dogs will need lots of exercise. Take your time to play with your dog and give it the attention it needs. Dogs that are constantly outside are especially prone to feeling lonely and bored. Give your dog chewing toys to keep it busy. You must also interact with your dog as often as possible. This will also alleviate its loneliness and boredom.
Maybe you should consider getting a second dog. Some dogs need company. Sometimes it is enough if you just let it meet other dogs. The company of another dog can be a valuable help to stop excessive dog barking. Some dogs barks because they want to communicate with other dogs.
However, perhaps the best way to stop it, is to train your dog. You can train it to avoid excessive barking, you'll need to train your dog. Dogs, like people, learn through association. If your dog can attract your attention through barking, it will do it as often as possible. You are actually rewarding it. Note that there are "good" barking, that has to be rewarded and "bad" barking, that has to be corrected.
You must reward your dog for this kind of barking, since it is needed and welcome. Pet it for a minute or so. Let the dog know this kind of barking is allowed. Believe me, dogs will know what kinds of barking are desirable and what are not, if they get the proper feedback.
Every time your dog barks without reason, you have to tell it to stop this behaviour. To reduce excessive dog barking, shake your hand in front of your dog. At the same time, simply say "no" in a very firm voice. Do not yell at your dog. And do not hit your dog either, this turns out counter productive for his behaviour. This could make him aggressive, which is the last thing you want. When the barking stops, reward your dog with praise. If it remains quiet for a minute or more, you can repeat the praise
Training a dog in general can be a bit of a mine field. There is so much to take in, what I have covered above just scratches the surface. To train a dog properly you really need to have some structure around what you do. There are many things that you need to take into consideration, such as exercise, diet, discipline, behavioural issues to name a few. I did a lot of research and tried lots of different things.
My dog Sammy is a Border Collie and had various behavioural problems, I tried a variety of so called dog training methods, such as different types of dog collars, books, diets etc. Some of these things did help, but the reality of it all was I had no structure or guidance from anyone to help me. Eventually I found my and now I understand why Sammy barks, he knows when its right to bark and when its not. Things are so much better for everyone, including the neighbours!!
If you can't train your dog without using pain, you probably should just get a hamster and call it good.
