Treat it like a baby Ace (A2, A3, etc.). Players see a painted Ace and get excited, but 15 other starting hands are better than AJ. Given that your opponents are probably going to be hanging onto Aces, Kings, or Queens in some form or another, your chances of becoming a huge underdog on the flop are pretty good. I strongly disagree that AJ should be played like AK. I do agree that flat calling with AJ isn't a good idea, simply because I think flat calling is rarely a good idea with ANY hand. If it's not good enough to raise, it's not good enough to play. Get away from it.