One of the first things that poker players learn when they start playing online is that premium hands are supposed to be played aggressively pre-flop. The reasoning behind this ground rule is solid, as you need to make sure that the number of players competing against you is limited to a handful. Even the best starting hands will lose their worth if enough opponents get involved so it is of critical importance to cull the competition.
As always, there are exceptions to the rule and this is what we’ll be talking in the next paragraphs, but the basic way of playing A-K pre-flop is outlined here http://www.cardplayer.com/cardplayer-poker-magazines/66223-joseph-cheong-25-26/articles/20992-playing-ace-king-preflop. The author encourages players to play conservative poker if they lack experience and if they face better opponents, as a straightforward approach will deliver better results.
Veteran players and those who spent a lot of time competing at either online or live poker tables, can experiment with slightly more complicated mechanics. To start with, calling pre-flop with A-K should only be done when you compete against skilled opponents, because there is no point in taking a leap of faith against beginners. The very reason for why the hand is not played in the regular manner is that you try to extract maximum value on the next streets, by disguising it as a weak one.
Assuming somebody bets and another one raises after you just called pre-flop, the decision is as good as many as you need to go all in or fold right there. The worst-case scenario is to run into pocket kings or pocket aces, in which case you are a huge underdogs while the more likely outcome is that you will play a coin flip. The upside is that by going all in you have fold equity and there is a good chance to win the hand right there, as your opponents will choose not to compete.
Back to calling with A-K, what you try to induce is the idea that you don’t have an ace or if you do, the kicker is very weak. You will win a significant amount against players who hold an ace and a face or a 10, in case another ace pops up on the flop. The chances for your opponent to put you on A-K are slim, so even if you check raise or re-raised the opponent, he will very likely stay in the hand. Just keep in mind that this strategy can easily backfire and you need to be willing to muck your cards on an unfavorable flop