Lots of lessons and tough to narrow it down to three.
1) Have a plan, and be willing to change the plan if he is not getting the desired results. We changed scope a couple times until we finally stumbled on the right situation. It was a lot of work, but I'm convinced after 20+ months we figured it out, and my son got the best possible outcome because of his flexibility.
2) Evaluate coaches by what they do, not what they say. Coaches will blow smoke up your butt...be prepared. They will tell you everything you want to hear. Young recruits get a false sense of secruity because they believe every word the coach is saying, but until they offer it doesn't mean anything. Until your son verbally commits, he needs to continue looking at new schools and keep the communication level high....no exceptions. Every time my son would cross a school off his list for one reason or another, we had to add at least one more school to the list.
3) Don't be afraid to say "no" or "can I think this over some more". Be patient and wait for the right fit based on your options. Coaches will only offer if they have a reason, typically they want to get a recruit before someone else does. It has to be the right fit to say "yes".