AK is a difficult hand to play. In the later stages of tournaments you can just shove it pre-flop and hope that everybody folds, or that if you get called by a pocket pairs, then you can win the so-called horse race.
In the early rounds of tournaments and ring games, it is tricky if you make a big pre-flop raise and get called by a player in late position and the flop misses you, and comes down with something nasty like T T 9 two-suited.
You have already put quite a lot of money in the pot, so you don’t want to just give up the pot, so you have to make a stab at it, but on the other hand you don’t want to throw good money after bad.
I think the best approach to this is to keep the pot fairly small with a min raise pre-flop, and then give away the pot if the flop misses you and your opponents are showing signs of life.
A better tactic perhaps is to go AK hunting. A player who does not raise much pre-flop makes a large bet pre from early position and you call from late position. Flop contains no Aces or Kings and villain is first to bet. He hesitates a few seconds, and then he bets half the pot. Either this means that he is extremely strong, or that he has Ace King and does not want to give up the pot, but does not want to bet the whole pot, which is already very large.
A player who has AA or KK is probably going to want to take the pot down now and not leave it open for an opponent with a good draw to beat him on a later hand. Remember that two pairs, not just straights and flushes and sets, can crack AA.
By putting in a large reraise here, you will often make him fold rather than try to draw to top pair, which may not be any good, and pick up a very large pot. Of course if he folds then calls, well, you may hit something on a later street if you haven’t already. This works better if your stack is smaller than his because 1) if he is well ahead of the game he may not want to risk losing a huge pot, 2) since your stack is smaller, you have more to gain and less to lose. If you have some kind of a draw, even a gutshot, this can tilt it in your favor. Opponent who has AK and nothing else is going to be pretty reluctant to call if there is a flush or straight draw on the board.