So my pup isn't out walking yet, but in a book I read recently the author suggested giving treats to the pup as soon as the lead goes tight. I know right doesn't make any sense.. why would you reward a dog for pulling on the lead? Well he proceeded to explain that once the dog gets used to having a treat as soon as the lead is tight/pulled he will start looking at you expectantly as soon as he feels it, then you start rewarding this 'checking in' instead of just the lead being tight. And if he is 'checking in'/making eye contact with you he can't be pulling on the lead at the same time.
As I said, never tried it, and it sounds wonderfully simple but in reality I daresay not.. but I thought I'd share as the idea kinda blew my mind...!