Partnership with someone you can trust and will trust you. Simple but well structured agreement insurance and book keeping, run like a business, and all accounted for.
After 7-8 years I can only say.....ask a few of the infamous ppruners here about how well my deal works. I must say I am the envy of all of them and my aviation friends.
Happy to discuss on the phone and email details and data on how to put it together.
Avoid more than 3. 2 of you is the best balance.
J