What is power in negotiating? Is it finesse? Is a real? Is it perceived? It could be all these things and more. Power in negotiating is defined by the book pass "the ability to bring about outcomes they desire" or "the ability to get things done the way one wants to be to to". The use of finesse in negotiations can be described as using your social skills to facilitate the negotiation process to get the results you desire. There are a variety of skills that fall into this category.
You could use friendliness to develop a relationship with the party or parties your negotiating with. This would build trust and a relationship of appreciation of each other's concerns. This could help you both look at the perspective and preferences from the other side. Praise would also fallen this category, this works especially well with friendliness. People like to stroked, by encouraging them to do well they are more likely to be receptive.
If you can also make an inspirational appeal to them. This relies on their personal values, hopes, and aspirations. Another way would be assertiveness, by making a strong compelling point in hope that they will heed them. You also can apply pressure in the right situations, but you should determine what you expect to get before doing this. Is your power real? If it is use your skills to present it.
If you're in a position of authority you may want to exercise that authority when negotiating. If you control resources you'll also want to bring them to play. You may be inclined to use coercive power from this position but this could do another roadblock in the negotiations. you could use these same resources if your power is only percieved.
Whether your power is real...