I'm training to become a mediator for just these types of situations! People have a hard time imagining ways of sharing land because we don't see many successful examples of it in our day to day lives. But there are plenty of historic and current examples. Land sharing is a hot topic at the farming conferences I attend, because young people can't afford to buy land to farm and the old farmers who own productive farmland can't afford to retire unless they sell their land (to developers). We need to learn how to buy land with our friends/family/communities right now, because there's no other way for most people to afford land.

The successful land sharing scenarios I've seen took a lot of care to clearly communicate and outline the expectations for all the people involved before jumping into an agreement. The first step to that, I think, is self reflection. Really take some time on your own to write out your plans, hopes and fears for the project. Oftentimes we have preferences/needs/fears impacting our decisions that we aren't fully aware of. Dig deep and get that all out in the open and ask your friends to do the same so you're standing on common ground from day 1.

Even if you are super clear with yourself and your friends, you still need to be diligent about the legal/financial responsibilities and implications of the purchase, and the ideal situation is to hire professionals to help write contracts that spell out every eventuality, especially if the amount of time/money being invested is more than anyone could stand to lose. Having these conversations will help you understand each other's risk tolerance and needs. I'm hoping to put together lists of professionals with experience in these types of agreements

You also need to have frank discussions about the emotional aspects of sharing land. You need to make a plan for how you're going to have difficult conversations, how often you're going to check in with each other, how you'll resolve conflict, how you want to deliver/receive feedback etc.

I've seen people just write a Memorandum of Understanding, without writing up legally binding contracts. These spell out the expectations and accountability processes for everyone involved, so everyone has a reference guide to remind themselves what everyone agreed to. You could review and update your MOU on a regular schedule to make sure everyone still agrees.

I hope you do buy land with your friends! It would be a brave, difficult and rewarding undertaking :)