How To Select An MBA Admissions Consultant

Do your due diligence. Ask past applicants what they have to say about working with the various firms.
Consider the professional associations to which the consulting firm belongs. These organizations (e.g., IECA, HECA, NAGAP, AIGAC, Better Business Bureau, etc.) have strict membership requirements and ethical standards that confirm the quality and trustworthiness of the firm and its consultants.
Have a direct conversation with the head of the consulting firm to align your goals and expectations. Be sure that you and the firm share the same view on your MBA admissions potential — before you sign up and pay.
Consider value even more than price. Saving a few hundred or even thousand dollars won’t be very comforting if you get second-rate service and fall short of your goals. Hourly services may look like a bargain, but a comprehensive consultation ensures that you discover and address all of your weaknesses.
Expect personalized advice that’s customized and shared with only you.
Trust your gut: the way the firm treats you as a prospect is indicative of how they will treat you as a client. Are they prompt, professional, empathetic, accessible, and responsive? Do they understand you and believe in your potential for admission?

Chioma Isiadinso, co-founder of EXPARTUS

Isiadinso, meantime, offers these guiding principles for those in the hunt for a good consultant:

You should start by vetting the admissions consultant. Find out who started the company, what is his/her role, how are consultants hired, trained, and what is the background/experience of the consultants?\
Find out who you would be working with and what their success track record is.
Stay away from the “fly by night” entities that make outlandish promises or have ethical flags (writing application essays, recommendations, etc)
Research different consulting firms to see which ones would be the best fit. Every firm is different in its approach, culture, focus. Some focus on strategy, some on essay editing/writing and others on both.
Have a preliminary call with the firms you are considering and assess the quality of the feedback they provide you (this can give you a clue to the quality of work they do)
Getting a referral from a friend or trusted colleague can be a good starting point so ask people in your network if they have any experience with the firms you are considering
Be clear on what you need. Have a realistic picture of what kind of candidate you are.