A good e collar with vibe tone and multi level stim is what I would recommend. Obviously there will be people against and for different training methods, but one thing I like of a good hunting e collar is you can use it in training prior to your walks, teach the tone, the vibe, and find which level stimulation your pup responds to. Then say your walking about and a Lil ole squirrel gains some unwanted attention, dog starts a pull, you give it a beep, if no response, they get a Lil buzz. I would also recommend that you have something to compensate for the prey drive, like if they stop on the beep then provide some enjoyment ie bumper, tug, that way they figure that not going for the squirrel pays dividends.
Not saying my way is the best or only, in fact I believe the opposite. There are tons of ways to train a dog. Hope you find one that works for you and are comfortable with
Howdy from Idaho!