In short, it is important that your attorney is admitted to the Illinois Bar and has experience with your type of case. It is not necessary that an attorney have any special credentials to practice collaborative law. However, there are professional associations such as the International Association of Collaborative Professionals and the Collaborative Law Institute of Illinois that require additional training in collaborative law and interest-based negotiations for membership.

In general, memberships, credentials, and training can provide some insight into the level of commitment of an attorney to a certain area of law. However, additional training and memberships are not necessary to make a good lawyer nor are they a guarantee against a poor lawyer.
I recommend speaking with an attorney face to face to make certain you choose an attorney who works and communicates well with you.