Have you ever seen those nature shows where scientists drag a fake seal behind a boat so they can provoke sharks to attack? The form of the helpless seal is irresistible to sharks, and they attack nearly every time. In a way, some professional poker players are like those ravenous sharks: they're looking for easy prey. They're searching for signs of weakness that will allow them to pick up pots with little resistance.
These pros can make life very difficult for an amateur. But there are ways that an amateur can take advantage of a pro's aggressive instincts. One useful play is called the weak lead.
Using a weak lead, a player bets out a relatively small percentage of the pot. For example, if there's 800 in the pot, the amateur would put out a bet of less than half – say 300. Looking at this bet, an aggressive pro may assume that his opponent doesn't have much of a hand. He may guess that the bet indicates some sort of modest connection with the flop or even a poor bluff. The pro may look at this bet and come over the top with very little, or maybe nothing at all. Knowing that a player is on the lookout for these sorts of signals means you can offer up a weak bet when your hand is actually very strong.
Say you're in a tournament and you raise with pocket Jacks. The pro calls behind you. The flop then comes 2-6-J rainbow, giving you a very strong hand. This is a great time to put out a weak lead. A small bet may entice the pro to believe you have something like A-K and missed entirely. He may raise right there, at which point you can decide to either call or pop it again. Or he may call your initial bet with the hopes of taking you off the hand on the turn. You can then check to the pro on the turn, and be all but certain that he's going to bet, at which point you can put in a raise.
Note that leading will often work out much better than check-calling or check-raising. A check-raise is going to scare off the pro; he may even lay down a pretty big hand when he sees that sort of indication of strength. And if you check-call, the pro will probably check the turn and then fold to a bet on the river.
The weak lead can convince a pro to put in a lot of chips on the flop. That may be the best way to extract the most chips from a tough opponent.