Important considerations when entering a joint development agreement with a large materials manufacturer?

Hi! My nanotech company has a lot of interest from large materials manufacturers. We are just now beginning to explore potential joint development arrangements. I was wondering if anyone in the community has any thoughts about how to structure for such an arrangement. I recognize this is certainly context-specific and vague, just looking for any general important lessons learned from anyone else who has jointly developed material technology with a large corp (e.g. 3M). Thanks!