My old dog rufus, when he was younger also pulled. He'd almost seem to be strangling or something, he has a weak windpipe. I got him a harness which seems to work, but hes also old now.
for my other dog, i started off using a pinch collar. It works really good to keep them from pulling, and to make them pay attention. But after (I had to use it for a obediance class) using it a while, I started to hate it more. It seems so cruel to me. The ppl tell me it its better then a flat collor cause it doesnt choke, but instead pinches a little to get the attention. I don't know if thats true, but I don't like it, and now use a gental leader. It works really well. But she doesn't like it, she tries to pull it off any time she can. The ppl i got it from said it takes time to get used to it, but she hasn't yet. Other dogs seem to be used to it, so I guess Jo just doesn't like it. From what I've seen her pawing at it, she can't get it off if its on right.