I personally think you cannot prepare much for these exercises - they are purposely designed so that you shouldn’t need to as otherwise individual people in the group would have a direct advantage.
Just go in with an open mindset, be flexible or adaptable in your approach to the task, contribute your thinking, even if it is through supporting or challenging others’ ideas, use any evidence to back up your thinking, bring in others to support your thinkin, bring in quieter members of the group when you can (they may have information that could be useful or your discussion), keep an eye on the time (it will go far too quickly), kee the tasks objectives in mind, and try to take some form of role if you can (time keeper, notetaker, brief reader, facilitator).