This is a unique combination framework that puts together the best of many other approaches to negotiation. It is particularly suited to more complex, higher-value and slower negotiations.
Prepare: Know what you want. Understand them.
Open: Put your case. Hear theirs.
Argue: Support your case. Expose theirs.
Explore: Seek understanding and possibility.
Signal: Indicate your readiness to work together.
Package: Assemble potential trades.
Close: Reach final agreement.
Sustain: Make sure what is agreed happens.
There are deliberately a larger number of stages in this process as it is designed to break down important activities during negotiation, particularly towards the end. It is an easy trap to try to jump to the end with a solution that is inadequate and unacceptable.
Note also that in practice, you may find variations on these, for example there may be loops back to previous stages, stages overlapping, stages running parallel and even out of order.
The bottom line is to use what works. This process is intended to help you negotiate, but do not use it blindly. It is not magic and is not a substitute for thinking. If something does not seem to be working, try to figure out why and either fix the problem or try something else. Although there are commonalities across negotiations, each one is different and the greatest skill is to be able to read the situation in the moment and adapt as appropriate.