There are a great many practices, behaviors, and skills that set great negotiators apart from more typical bargainers. Indeed, enough to fill an entire book.
Probably the single most important of these, however, is preparation. To put it plainly, the best negotiators prepare fully and carefully for any important negotiation.
It is no surprise that negotiation professors emphasize this stage of the negotiation process so often and so emphatically.
If I were permitted to give you but one single piece of advice for improving your negotiating, it would be this: if you prepare fully for each negotiation, you will achieve better results.
It is that simple. As a general rule, the more prepared you are, the better your outcomes will be. In any important negotiation matter, take seriously the various acts of getting ready. Prepare as would an actor before a big performance, an athlete before an Olympic match, or a lawyer before a major trial. Do your homework! Preparation is something within your reach that can directly improve your results. It is there for the taking. Take it.