The IB Principles to Practice are worth reading – in particular in relation to the exhibition. Figuring out the purpose of the exhibition, how it will look in your context, what roles each member of the learning community will play, and the degree of release toward a student-led exhibition, are key factors to consider before getting started.
How you determine the style of your exhibition will depend on knowing your learning community and thinking of how best to meet the needs of your learners. Some people may benefit from a guided approach while others will flourish given the opportunity to lead their own learning. Find an approach that best supports each learner in your community.