Dottie was a MAJOR puller on the leash, yanking me spastically down the sidewalk with her for about 1.5 miles each day. My arms were very sore after 2 days of her dragging me around.

I found the following advice by Cesar Millan, the Dog Whisperer, to be indespensible...

Place the collar or loop directly behind the dogs head, not down on her neck. It will probably sit just behind her ears. Think of dog shows, where the loop of the lead is placed up close to the head. (info found in the book Cesar's Way) (ETA: not a direct quote)

I placed her collar as advised, and kept a short firm lead (not tight, but not slack - again, like a show dog). She held herself much more proudly and just fell into place and trotted along side me. No pulling at all. No choking either. It was amazing!! I chose the right side, as I am right handed, and know nothing about right or left for 'heel'. That was all I did. I did not say anything to her, nor did I give her treats. I praise her occasionally. And walks became enjoyable, instead of struggles of will. We also practice sitting at intersections and at other times on our walks. I praise her for good sitting.

Our walks are for exercise. After the first 2 days of her pulling and sniffing every blade of grass, I realized she never pottied while on our walks anyway. So I take her out to potty first, then we go for exercise. For potty purposes in our yard, I let her sniff about on a loose lead. She (almost) never pulls when she is smelling out a place to 'go'.

HTH