Negotiations can seem as complex as physics, and in fact, people go to college to study the science of negotiating just as they would the laws of nature. At the same time, negotiation is like an ancient art form, some sort of Zen mental jujitsu. When neither the Zen nor the science works, though, no one wins.

Just ask any hockey fan out there. The recent lockout and cancellation of the 2004-2005 NHL season is a perfect example of poor negotiating. Both the players’ union and the league owners broke all of the rules when it came to brokering an agreement on player contracts. The result are hockey rinks across North America that are so quiet that you can hear a pin drop—unfortunately, not a puck. In dollar terms, professional hockey is missing out on television contracts, advertising fees, and tons of ticket sales.

Of course, you won’t lose billions in revenue if you fail at the latest negotiation at your favorite online classified or auction site. But you could let a treasure slip through your fingers. Success in deal making, on the other hand, could land you that rookie Bobby Orr card, signed Stanley Cup puck, or whatever other fantastic item you’re bidding on.

Plus, proper negotiations and compromise can ensure that you get the item for its fair value, including a good price on shipping and taxes. This increases the profitability of the trade for both you and the seller. The deal gets closed without nasty disputes, blow-ups, or hip checks. And both of you are left to do business again in the future.

To score all of these benefits, and avoid your own mini lockout, follow these simple tips on negotiating that will net results at online classified sites. As you’ll see, victory isn’t so much an exact science or a mystic sixth sense. It’s more about simple know-how and common sense.

Warm up. Don’t jump into a negotiation cold. Before you even face off with your opponent, figure out for yourself what would count as a victory. What do you exactly want out of the trade—and at what price?

Consider a truce. It may not even be worth dropping the puck at all. In other words, negotiations, like hockey games, can end in a loss for the home team, you. So weigh this risk before you start. If the item at hand is a dream buy, you may not want to endanger your purchase with a drawn-out negotiation.

Know when to pass. On the other hand, if the item is far from dreamy—and you’re pretty sure something better may come along later—you could pass on negotiations. Or go for the score. Offer a lowball price. If you win, you won’t be out too much, and if you lose, it won’t leave a mark either. But be certain if you play this game. You could miss this opportunity without a guarantee of future prospects.

Know your enemy. Coaches and players spend hours before games watching films of their impending competition to study their tendencies. You need to take the same approach when it comes to making a deal. Try to read your opponent’s mind. What is his or her goals in the negotiation? Does he or she have any strengths that they can use against you? Are there any weaknesses that you can use against them?

Spot all of your passing lanes. During your research, you may find that this particular vendor isn’t the only one in the game with what you’re looking for. Using these other vendors, and their prices, to your advantage can help you skate circles around your competitor.

Practice before you play. Also, research the item before you make a play on it. This knowledge, such as the going price and quality markers, can work as leverage during the negotiating, too.

Translate thought into action. Your strategy can become more complicated and unpredictable—and effective—once you’re in the heat of battle. Just remember to think on your feet and remember all that you learned in your “training.” For instance, if you know that the vendor has other items for sale besides your target, agree easily to one of these other purchases. Go for the easy one first. That will lure them into trusting you and giving you an easy pass on future, and more important, deals.

When it comes down to it, negotiation is all about this kind of give and take. It works out best when both parties get what they want out of the deal, without feeling ripped off as if they gave too much for too little.

That brings you to the one “don’t” of negotiating. Don’t fear a standoff. They are part of the art and science of trading, so don’t be tempted to cave in just to break the deadlock. Instead, let your opponent make the first move. They will. They want to close the deal, too, don’t forget. You both will be better off for this in the long run. And you won’t end up like the NHL, the No Hockey League.