Start by putting a little muscle memory into your call. You want your dog to respond to your call automatically, without weighing his options! This should be done on your 6′ walking leash.
As you regularly walk your dog, randomly call him to you. As the dog turns to you, back up until he reaches your body. Condition your dog to come in close by feeding him a treat close to your knees or shins. Dogs are hard-wired to follow movement. If you are standing like a statue when you call your dog, you are the least interesting thing in the environment.
You are using the same method for the 6′ recall, but will gradually increase your distance from your dog. Attach a 30′ training lead to a no function body harness. Once your dog is coming when called at 10′ distance, increase it to 15′, then 20′ and so on. Never move to a longer distance until your dog has mastered the current one.
