Expert handlers trust their dogs and their dogs trust them. It's a 2-way street! First, let's discuss what you can do to help your dog trust you.
Helping Your Dog Trust You
One of the best ways to build trust in your dog for you, is to be a good trainer and follow the Dog Training Psychology motto: "Take Small Steps to Perfection." Keep training sessions fun and short. Do not loudly scold your dog, except in emergencies.
Small Steps. If, for example, you are training your dog to run into the proper tunnel entry after taking a jump don't expect perfect behavior right away. If you expect too much and she fails and you scold your dog loudly, she will stop trusting you. Esteban of BadDogAgility likes to explain that he helper his Golen Retriever to be a speed demon by always making practice fun and never scolding in a loud, mean voice.
Remember, your dog is always right!
Many dog agility handlers, even top performer, don't understand this, but it is true. If you dog seems to fail, she is actually doing exactly what you told her to do. Look at yourself. Modify your own behavior. Back up and make the task easier for your dog.
Some trainers who understand this principle, even reward their dogs, when the dogs fail to perform as they would like,
because they know the mistake was theirs and the dog was trying its best to follow.
Trusting Your Dog
A good way to learn to trust your dog is to practice a lot and reward your dog profusely when he/she performs as desired. After a while you just know that once you give a cue your dog will listen and perform as desired.
If ever you are disqualified, early on in a trial, use the rest of the run to test YOUR trust of your dog to the max; that's how I learned to trust Momo's table stay.
Look at experts when they walk out from the start line. They trust their dog so much they don't even look back until they reach their lead out position. I even sometimes dance out, practicing my salsa or cha moves and then give secret hand signals to Magic Momo. (a humorous move that helps me be my best).
Watch the video titled "Momo Earns Blue Ribbon..." Notice how I trust Momo as I go out to my lead-out position. And notice how after Momo jumps onto the table, I go forward and position myself by the next jump while she waits for a cue to take off running! Several other handlers have not learned to trust their dog and have to stand at the table like a policeman.