3 Friends - Investing together

[Phillip Forrence]

My three friends and I want to start real estate investing as we've caught the BP bug. We have read Brandon Turner's book on real estate investing multiple times, reached out to local realtors, and made spreadsheets analyzing deals. 

We're looking to make our first offer in the next few weeks, but thought of a problem. What if something goes wrong between us? What is the best way to protect ourselves legally and structurally from each other in the many worst case scenarios?

Thanks in advance