I found him a used bike, helped him pick out some safety gear, and had him take MSF BRC to get some basics and get legally licensed. At that point he was fully qualified to ride around a parking lot at 20mph.

After that, I took him out to a local large empty parking lot and had several two hour sessions with him having him do a variety of drills. I also put him out on a local, non-busy street for an hour or so at a time to practice shifting and braking and get those somewhat built into his "muscle memory."
Then it was time for him to hit the streets. Fortunately, we have nearby a long road along a lake with a low speed limit, no cross traffic and varying turns which seems to be a good road for our little training rides.
So, here's the rub:
I'd always heard that when riding with noobs that the least experienced rider was supposed to ride in the front. We tried this on our first ride and it went disastrously. No accidents or anything but he hept fixating on his speedo and worrying about how fast he was going, braking all of the time, being paranoid about going too fast, not looking far enough ahead and generally being a total dork. In fact, it got to the point where I just didn't think it was safe so I ended the ride mid-way, took him home on my bike and then went back and got his bike. (Boy, was he mad! Although I finally got it through his thick skull that the reason I called it off was for his safety.)
So, for the next ride, after teaching him a few hand signals, I took the lead. Things went MUCH better. (I also put some tape over his speedo and wrote the words "LOOK UP, RELAX, BE SMOOTH".in large letters on the tape. His new acronym is now LURBS

So, at least for a total noob like my brother, I've come to the conclusion that it's best for the more experienced rider to be in front. Some of my observaions on why this works better (at least for my brother and me):
1) He doesn't have to worry about speed and keep looking down at his speedo. I've promised him that I will NOT go more than 5 over.
2) I don't have to worry about him not seeing what dangers (e.g. pedestrians or cars) lie ahead as I am essentially blazing the trail.
3) He doesn't have to worry about navigation. (There are a few options for turns, etc... on our traning route.)
4) I have pretty decent mirrors and since we're only riding in the 25-35 range, I can watch his technique for giving him pointers.
5) Since I"m in the lead, if I do see any glaring mistakes on his part, I can pull us over at the next safe spot and give him a little mid-ride debriefing. Even if I don't see any glaring mistakes on his part, I do pull over every once in a while so he can relax, get some minor pointers from me and ask any questions he has.
I suppose that after a few more of these rides, I'll put him in the lead but for now, having the more experienced rider in the lead seems to work much better for us.
Just curious about the experiences of others who have helped someone else learn to ride.