You are going into business together; so, it's common to jointly sign documents.The biggest risk challenge is putting your friendships at risk. 

@Gregory Pitts - it speaks for your personality that you don't want to take something for nothing, but mentorship is like friendship - you can't buy it.I have been an investor for more than a decade and sometimes host a meetup as a member of our local group or talk about a topic - and I am happy to answer questions and volunteer my time - but once in a while someone wants to buy me coffee in exchange for some what you have to label as nothing short of "serious consulting work", basically listening to their entire life story and then helping them develop a strategy to go from zero to hero.

It will definitely put the friendship at risk.

While apartment investing is exactly what I do personally, in the interest of keeping a good friendship intact neither one of us is interested in my teaching/training him.

The fastest way to ruin a friendship is with money.Second - I would advocate your lender get a lender's title policy, and their lien would hopefully be the first lien against the property.

You need to find that flipper first  before you would go looking for a deal to partner on and earn their trust / friendship and show them your work ethic… maybe assisting them in their project.  

Look forward to many new friendships and partnerships.

Best friendships have been ruined in business partnerships, mostly because everyone thought "We are all friends...we are good here, we need nothing in writing!"

My definition of a banking relationship is a business account with the bank to start out, then a history of successful loan payments.Some people think it means work with one bank and have dinner and cocktails with an employee of the bank--personally I don't think that.I think unless you are one of the banks "High net worth" clients using that service, your interest rate and terms will be about the same flexibility as another borrower with your experience, and credit rating and financial picture.I think the "Old Buddies" system of granting credit went out with the Horse and Buggy, replaced by the computer.Not to say that ABC Lenders might not be more flexible on terms, or willing to cut you deal on some other aspect of the loan if they really need to make the loan, or it serves some civic purpose (maybe neighborhood revitalization, etc..).It seems to me the computer is going to dictate the terms and policy (not personal friendship with an employee) and will dictate allowable modifications.If I am wrong on this, BANK LENDERS let me know.I am talking about Bank relationships here, vs Hard Lenders or Independent Brokers.Just my 2 cents.The Old Buddies system of Loans: https://www.youtube.com/watch?

The questions I get are not out of courteously with the intent to learn but more so out of jealousy and has strained at least one friendship.