One of the most common alternatives to a collar is a harness. Veterinarians routinely recommend that dogs, such as pugs with their short noses, and miniature poodles with their propensity for collapsing trachea wear harnesses. However, it's important to chose the right one. In general I avoid harnesses that hook on the back unless you want to train your dog to pull a cart or a sled. These harnesses actually help train your dog to ignore you and pull you because when you pull on the leash to try to gain some control, they direct the dog's attention away from you.
The next step in training dogs with a head collar is to train them that when they reach the end of the leash they are going nowhere. That means the owner must hold perfectly still and avoid taking a step or even moving the leash-holding hand. Once the dog figures out that pulling harder does not work and instead steps back or turns to the owner such that the leash is hanging loose, then the owner can resume walking. Better yet, the owner can reward the dog with a treat so that dog comes all the way back to her and then they can resume walking forward. It's important that the dog learn that a tight leash and the associated pressure created means she should stop. If the dog is not taught this and tends to act impulsively, she may dart out after a cat or other object and hit the end of the leash with some speed. This type of accident could potentially cause neck pain or injury. Even in the emergency situation, if the owner is paying attention, they can prevent neck wrenching if they gradually tighten the leash rather than letting the dog dart forward on a loose leash so that she suddenly hits the end.