I had the same problem with my now two and half year old, Willie. He never learned to walk properly on a leash, and since he weighs almost as much as I do, he had to learn. What I did first was just randomly say, "Willie, don't pull!" and give him a treat for coming to me. When I knew this was solid in his mind, I put his leash on and walked around the backyard. Anytime he'd start pulling, I'd tell him "don't pull" and he'd come get his treat. When he wasn't pulling I CONSTANTLY praised him and gave him treats. Good treats, too, cheese or hot dogs or something. After we got it down in the backyard, we tried on the street right outside the house, where there was nothing new or exciting for him to pull towards. It was a little harder here, but I just stayed consistent. Anytime he pulled, I'd stop, give the command and wait. And wait, and wait, sometimes but he eventually got it. After about a month of this, he is very reliable on the leash and we go all over town without pulling. Hope this helps!