One absolutely proven and guaranteed way to train any pet!
Whatever route you decide to take in training your pet, do it yourself or hire a trainer, you must be consistent. Once the pet has a clear understanding of what the rules are they will happily follow them.
The true key in training your animal, specifically your dog, is training yourself. When you give certain commands to your dog, keep your tone constant. For example, when you are telling Spot to sit while you are in a good mood, don't change it from when you are in a bad mood. Do not let it go from "O sit baby" to "SIT YOU STUPID DOG!!!
This sort of action only confuses the animal, and then we tend to think they are being disobedient. The truth is that as much as your dog loves you, you are starting to confuse and irritate them.
As much as we hold conversations with our pet, they really can't understand our dialogue. The only thing they really understand is tones and sounds. This is why being consistent with the tone of your commands is important. I think it is a good idea to talk to your pet, they know when you are loving on them.
Once you make up your mind you want a well trained animal, remember it all starts with training yourself first. Never begin the habit of repeating commands, or they will be less effective. For example if you say "down down down" your pet will think if you do not say it three times you are not serious.
Be sure to understand that you must train yourself to be consistent! No matter what route you want to take in training your dog if you stay consistent they will continue to be that great extended part of your family!