I agree with practicing everything you do to become proficient at it, but practicing alone won't tell you why you failed in a task and can not give you pointers on how to improve upon something. like I said up top, if you are having problems or just want some pointers, a few admins make beginner squads. But if you don't ever get the chance to get on with them, then just hit me up around the times I'm on (2200-0400ish zulu) and I'd be more then willing to get on and rock it with you and get you proficient. I'm just not sure your going to get anyone to actually set up a server or time for a course or lesson that maybe only two or three people would attend, It's easier to just run in a squad in game and learn as you go.
I'm not big on the idea of a "school" for a game that almost 90% of the people play for fun. I understand where your coming from with the suggestion and I've seen a lot of new players as of late, but to be honest, those that would need the training the most are the ones that likely won't attend, and a very large majority don't come onto the forums. I know a few admins on here make a squad just to teach new people the ropes on the coop server and I'll stick around new guys and give them pointers where it's due but from I've learned from my days playing Arma milsim is that schools in a game don't teach anything more then you would learn playing the game normally with experienced people. Not to mention it 'can' be dreadfully boring for those in attendance. If anything, I recommend more "on the job" training then a school or course, people will learn faster and retain the information better if actually doing it and having fun with it.