Pulling on a leash is typically not a dominant behavior. Walking on a leash is not normal to a dog, if you do not teach them and show them what you expect them to do, they will do what comes naturally and that means to pull and try to go whatever way they can. Some dogs do naturally heel and walk next to you, others you actually have to teach.

But luckily, teaching heel is actually pretty simple. You don't even need a leash to begin with. Just call your dog to you and lure her into the heel position with a piece of food while saying heel. When she gets there, give her the treat. Then walk 2 or 3 steps while saying heel. Sometimes it helps to put the treat up near your face at your chest so she's focused on you and looking up at you. I also find it helpful to keep the treat in a balled fist, this makes it easier to fade the treat. Then give her the treat after those few steps. Now snap the leash on and do the same thing without holding onto the leash; let it drag first. This is so you can eliminate any previous experiences with the leash like pulling. Many times, you can teach heel and the dog is great at it, but if you just snap the leash on and go out, it won't work and it'll seem like the dog was never trained in the first place. Once you can snap the leash on and she doesn't get overly excited, then pick it up and again do the heel exercise. By this time, you should only be giving treats periodically and the primary reward for the dog should be praise.

When you first go outside again, it may be helpful to take treats with you so she stays focused on you and obeys as there are along of distractions out there. It also helps to keep talking to the dog in baby talk, telling her she's a good girl, making kiss noises as you walk, so she stays focused on you. Eventually it'll become habit to walk nicely at your side.

If she starts to pull, the best thing is just to stop, don't say a word. She'll probably look back at you, puzzled as to why your not moving. Have her heel and then keep going and don't forget to praise her.

Your probably reading this thinking it's a long hard thing to teach, but really it's not. A relatively intelligent dog will often pick up on it in one training session. Some dogs you will have to work with for a few days, but it's really not all that difficult to teach. Just be consistent and be patient.

I allow my dogs to walk ahead of me as long as the leash is slacked.