There are several cardinal rules to negotiating effectively. One is do your homework, and learn as much about the seller or the buyer as you can. Another is to play your cards close to your vest and not reveal too much information to the other party or their agent. Don't let yourself get rushed into any decision, no matter how tempting it may be. Finally, if you have doubts about your negotiating skill, hire someone to help.
Remember that the listing price is what the seller would like to receive but is not necessarily the lowest they will settle for. Before making an offer, check the recent sales prices of comparable homes in the neighborhood to see how the seller's asking price stacks up.
Full-price offers or above are more likely to be accepted by the seller. But there are other considerations involved: