Teaching Focus

I had read a thread on here before, I believe the thread was actually called "Teaching Focus", and it showed a good example of how to teach focus. Something along the lines of putting treats in both of your hands, close your hands into fists, letting the dog sniff the treats in your hands and then stick both arms out on both sides and give them the treat when they focus on your face and not your arms/hands.

I would like to learn more little "teaching focus" methods like this.

My 18 month old neutered WGSD, Doc, is currently is going through a phase of lunging at people walking by while we are on leashed walks. It started where he would just do a friendly jump to people that came up to me, and after that, I tried to prevent him from doing that by holding him close to me with no slack on the leash (and I found out from this board that by doing that it makes it A LOT worse!). So after lunging at 2 people and nipping at their clothes... I have been working a lot with him on our walks. I have been avoiding paths/sidewalks that I wouldn't be able to step to the side and be out of reach for the dog to lunge at the person walking towards us. I have been working on getting him in a sit/stay anytime a car is driving by or if there are other people/dogs in sight (but not close enough to get to). He is doing very well so far with that, but he still focuses on them. I don't trust him enough yet to let him walk past an approaching person that is within reach. I would like to get to the point where I can walk him on tight sidewalk with tons of people walking past us without him lunging or better yet, without him paying any attention to them.

I am also hoping that since he is in full blown adolesence right now, I am hoping once he matures that he will be less protective/aggressive/distracted. He is my first GSD and it has been a long journey, learning new things all the time.