Can someone please tell me the most appropriate way to split ownership for the following:

My friend and I are going to purchase some investment properties(multi-family rentals and potentially some single family fix and flips). I find the deals, manage the properties, and complete all restoration and repairs as needed. My friend puts up nearly 100% of the cash needed to purchase the properties, so the 20% down payment for most situations.

What is a fair way to split ownership?