The number one, most important thing you can do for your dog is to be trustworthy. Trust is built over time by showing your dog that they can count on you to act in a way that is appropriate and reliable in every situation. Have you ever noticed that a person that has to tell people to "trust me" is NEVER very trustworthy? This is because trust is not something bought and sold through lip service. It's held in equity and built over time by performing actions that make small deposits in the "trust" account.
After starting with the assumption that you are not putting your dog in situations that are way over their head, there are three key elements to building trust with your dog, and responsibility in them:
- Be believable in your response to things your dog does right
- Be believable in your response to things your dog does wrong
- Be consistent in 1 and 2
Whatever response you provide your dog when they do things you like should be genuine from you and valuable to the dog. The same goes for when they do something you don't like. How can you clearly qualify the two? A calm tail wag, eye contact, taking food rewards, and movement toward you are all good indicators that the feedback you are giving your dog is well received. And if you are trying to address an incorrect behavior, immediate cessation of that undesirable behavior is a pretty good indicator that you were clear in your communication that what they were doing was not appreciated. This doesn't mean that you reward a behavior or correct a behavior once and it will never come up again, but you should be able to clearly qualify your reward or correction as effective based on the feedback your dog gives you.
There's an underlying issue of magnitude in your responses as well. If you lavishly reward something that took minimal effort, expect your dog to feel what they did to earn it sufficient in all situations moving forward. Likewise, how you address a dog popping up out of a sit should be probably be an order of magnitude less than how you handle some more serious infraction.
Lastly, it's rarely necessary (and often counterproductive) to provide negative or positive feedback that is high in intensity, provided that you are adhering to good training principles like thresholds (a topic for another post). In places where most folks would raise their voice or alter their pitch, all that is usually needed is more follow through (which amounts to more patience) in their response rather than more exaggeration.
Be the person your dog can believe in. Consistency and reliability in your thoughts, emotions, and actions will create consistency and reliability in your dog.