• Scope - do they understand what you are trying to accomplish with this project
• Process - is the framework solid, but flexible enough to meet your requirements
• Skill - do they have the right skill sets for your project
• Price - are the costs clearly outlined, including scope change order process
• Time line - how long will it take to deliver (beware the overly aggressive time lines)
• Personnel - who will work on the project
• Trust - make sure to get at least three referrals

Be sure that your team has agreed on the criteria for decision making. This can be a formal worksheet or an informal bulleted list with weights.

At the end of the day, when buying professional services, you are buying people. Do NOT short change this aspect of the decision. If you are uncomfortable with the people from the beginning, it's only going to get worse. Choose people with whom you feel you can have a comfortable, professional relationship. You do not want a new best friend, but chemistry is critical.