If you observe a litter of wolves, the dominant pup will show dominance by steering the heads of the more submissive pups.  When you use a head collar on your dog, you are basically the alpha dog or the pack leader.  These collars work very well, and you will have success if you get the dog use to the collar gradually.  When you first put it on, the dog will try to rub it off against some surface or with its paw.  The best bet is to place it on the dog for a few minutes and take it off, and extending the amounts of time you leave it on before removing it.  You'll find you will have better control walking a dog that loves to pull.