At first when we were in service dog training class and Coco graduated from the obedience part of the training, I thought, we are going to teach our dogs to watch us? Coco hardly ever takes her eyes off of me. But much later I saw the wisdom in it.
You begin by taking a small treat and you hold it in your hand behind two fingers. You use those fingers to point to something on the ground or on a table or at your face and when your dog looks at your fingers you give them the treat and praise them. You get them to sit and put a treat on the floor, just out of reach, as far as you need to and you put them on a sit. And every time they look at the treat you tell them to watch you. When they do, you give them the little treat. At first it is a few seconds but gradually you get them to do this and stay sitting and watching you move around a room with a favorite treat just out of reach and they stay there. I can put Coco's favorite treat on the floor in front on her and leave the house, close the door and walk around to the back door and open it and come back in and take my time doing it and find her watching me and laying right there until I tell her she can have her treat. This impulse control developed slowly over the course of a year of intensive training. But man oh man, when she understood it, she applied it to every thing she did, every where we went.
All of this builds the understanding of what you want them to do. In your home where there are no distractions. Then you do this training in the park. At first during quiet times of the day so they are not distracted by other dogs. When your dog pulls the least little bit you go in the opposite direction. Give them a sound before you do it and make sure they see your back. Use your two fingers to point to the ground and drop a treat there. Back in focus. You provide the greater distraction. You are like the mother dog. Puppies may wander but they always know where their mother is. And when she looks at something or has food they come running to see what she is up to.
When Coco was learning complex commands that were crucial to my safety I used raw meat as her treats. I have peripheral blindness and Coco is trained to keep me from walking out in front of anything that sounds like an engine is on. She has saved me from walking in front of cars many times. Now I always watch her too and I stop when she cues me to stop and look in the direction of the sound of a motor. If I tell her I see it we're safe and the car is pulled over or has stopped for us, then we go. If I am distracted she cups her body in front of me and stops me until I look at what she wants me to look at. Of course, my girl is always right.
Her focus is always on where we are going. Maybe some of these things will give you some ideas that will help you and your dog to find that common language. Whether Coco is on a 30 foot leash or a 6 foot one she knows that if she pulls I will always go in the opposite direction until her focus is where is needs to be. The very first time there is a little bit of a pull this consistently happens. Some times I will back up so she is always watching to see what I am doing next. It must look like a dance to people who don't know what I am doing.
I am also sensitive to her curiosity and when we are having some free time, so long as she isn't pulling, we go and check out what interests her too. So we are considering each other. No tug of war. Its more like a dance, a gentle moving together in the same direction. Some times I tell her, "Mama follows Coco" and she walks in front of me and is constantly checking on me to make sure I am with her. It is a beautiful thing to see.
Here is a video when Coco was learning focus at the park on a long leash.: