1. Experience + Industry Knowledge
Who and why are you considering this firm? What are their past experiences and expertise? Who is going to work on your project? More than likely you are looking for a strategic strike force that delivers good value, over paying a cumbersome army.
Having the right chemistry and cultural harmony with the firm is very important. You don't want to feel stifled or overshadowed while engaged on your project. You should spend some time with the prospective firm to assure it is the right fit for the specific job.
Communication is king! More often than not, a firm will send in its 'A-team' to a pitch for your business only to swap in a junior team once it is awarded. Although this practice is waning, you should know exactly who is working on your project and what their personal experience and expertise is. You should also be able to contact them freely without a layer of filters.
4. Understanding the Industry + Business
Is the team comprised of good listeners? A key attribute is the ability to communicate well. Does the firm understand your problem statement, and are they asking the right questions? Is their strategic process in line with your business requirements, and are you comfortable discussing every aspect of the program with them because you should.
5. Response to the Brief
Is the proposal insightful? Is the proposed process sound, and do they understand the objectives and constraints? Do they understand your brand, the target audience, marketplace, and manufacturing target prices?
6. Transparency + Value
At the end of the day, clients want to have confidence and reassurance that the firm will help accomplish the business goals at hand in a competent and professional manner with no surprises!