For technical vendors you want to define the following:

• Define how the vendor and your staff will collaborate.

• Identify specific milestones that the vendor will be responsible for.

• Determine how vendor work will be reviewed.

• Develop a method for identifying, analyzing, and resolving issues.

In some cases, you are going to want to outsource a specific business activity or process. For political vendors the situation is fuzzier. You should define a specific set of milestones related to permits, licenses, permissions, and other work. Then you can begin to assess how you will measure the performance of the political vendor.