Negotiation, by definition, involves another side. Therefore, the other side's behavior will affect the outcome of the negotiation. Negotiation, then, requires you to predict the behavior of the other side when faced with choices that are created, in part, by you (for example, you've offered to pay money if the other person will do something for you). But, there are almost always other choices the other side can make that are in the background, usually unknown to you (for instance, another more attractive offer). Negotiation experts teach various methods to smoke out these other choices so you can react to the other's possible choices. Most of the techniques involve asking questions and putting yourself in the other's shoes to speculate what you would do if you were in the the same situation (always hard to do).
But, you will almost always be operating with imperfect information about the circumstances the other side is facing. Operating with imperfect information is a key characteristic of developing a strategy. If you had perfect information about how another side would behave given specific stimuli, you would develop an action plan to provide the stimuli to achieve the result you are seeking. You wouldn't have to develop a strategy since you know how to cause the outcome you want.
So, negotiation involves dealing with imperfect information about how another will respond to certain stimuli in order to achieve the goal you've set, just as strategy involves dealing with imperfect information to achieve a goal you've set. But, strategy usually doesn't have "another side" who is affecting the outcome. Strategy may have many "other sides" that will react to actions you take. Further, the information on which you base your strategy will be imperfect. So, we usually see probabilities assigned to likely outcomes if you follow a certain strategy and these probabilities are, at best, educated guesses.
In developing a strategy, you use the same thought process as if you were negotiating with each of the "other sides." You will gather information in order to predict the outcome of actions you will take. But, unlike negotiation, you will not have direct feedback from "another side" when you take actions. You will see results over a period of time and not know, with certainty, whether the actions you've taken produced the results. On the other hand, like negotiation, you will have to react to responses you are observing, hoping to understand what these responses are being caused by and changing your strategy or tactics accordingly. Should you react or should you stay the course?
Preparation is the key to successful negotiating. Preparation is the key to developing an effective strategy. Preparation for both of these requires you to set clear, measurable and achievable goals. Setting these goals is usually easier in negotiation because of the focus of the negotiation. But, a common mistake in both negotiation and developing strategy is to give superficial thought to setting the goals resulting in "fuzzy" goals. Having fuzzy goals always results in fuzzy strategy. Fuzzy strategy in negotiation leads to underachieving the goals just as fuzzy strategy in a business context leads to less than desirable results. Consciously forcing yourself to step back and spend more time on setting clear, measurable and achievable goals when preparing for negotiation or developing strategy is the most important use of time for a negotiator or leader.