i was gonna pull up an article for you about blind defense but just realized it was in the Gold Section so it wont be available to you yet. but maybe some gold members who read this might want to check it out.
http://www.pokerstrategy.com/strategy/bss/1615/1/
as for the actual hand, here's my two cents (im nowhere near a coach btw)
vs a total unknown, i would probably fold it preflop because it's really difficult to play in a sandwich between 2 players.
if it was only sb vs bb, i dont really mind 3betting as you did. (i think i might call with broadways and hands with better playability, but A6o isn't really one of those hands). but in reaction to 4bet, if he was nit/unknown or had not done this before, then i think maybe we should find a fold.
p.s. at the way the hand played... i cant believe 4 bet bluffing goes on in NL2. have the games really gotten that much tougher and more aggressive?