Well the best advice I can give you that you might not have already thought of (of course you need to get the football side of things so I won't bother with advising you there) is to find a great teacher -- and I don't mean of the game but a great teacher period.
It doesn't matter who he or she is or what subject they teach. Find someone who connects to their students, and knows how to take even the hardest subject and explain it in simple terms and pay attention to what it is they do and how they do it. THAT is the key to coaching and leadership in general, imo.
Anyone with brains and determination can study and learn enough to coach a team but the key is in finding how to transmit the information in your head to others. We all know brilliant people who can make 1+1 hard to understand because they're missing the knowledge of how to teach others. You want to find someone who can make E=MC² sound like the easiest thing in the world to learn AND make you excited about learning it even though you didn't care about the subject beforehand.
If you can find someone who makes you want to learn your most hated subject then you've found your man or woman.
ETA: And one other thing... when you teach or coach others, never pretend you know more than you do. Own up to not knowing something and tell them you'll find out. People whether they're young or old can smell bs and you'll lose their trust in a heartbeat.