One of the most common requests for assistance that GRRA's Canine Behavior and Training team receives is training a dog on proper leash walking. There are all types of distractions that can trigger a dog's behavior to sit, pull, lunge or bark during a walk. These behaviors can be driven from fear of unknown situations to simply not knowing how to walk on a leash properly. For any of these scenarios, training a dog on proper leash walking takes time and positive encouragement. Here are a few simple steps to train or retrain your dog on leash walking:
Start inside, to minimize distractions
Introduce or reintroduce your dog to the collar, leash, and harness
Practice leash walking inside
Then practice outside -- take small steps: start in your yard or small area and then expand
Always encourage, reward, and reinforce for following your cues, do not force your dog - time and patience with leash training will get your dog walking properly.
For additional information on proper leash walking, attached are references from AKC and Chewy.