Negotiation is a process between self-interested buyers and sellers in a business transaction trying to reach an agreement on one or more issues. The outcome of the negotiation depends on several parameters such as the agents? strategies and the knowledge one agent has about the others. It is important that an agent chooses a proper negotiation strategy based on the available information in order to achieve its goal. In this paper, we first perform a comparative evaluation of commonly used negotiation strategies for bilateral single-issue negotiation and show that there is no one strategy which works well in all situations. We then present an adaptive negotiation strategy that a seller can use to increase its gain. The strategy adapts itself based on information obtained about the buyer?s strategy from an ongoing negotiation process and past negotiation experiences. We present extensive simulation results to show that for a wide variety of cases, the adaptive strategy gives better performance compared to the best non-adaptive strategy found from the comparative evaluation done earlier.