Go over terms on the sale you both want to see on a scratch piece of paper .. then give that to your lawyer ..Your lawyer should draft up an agreement and send it to his sellers lawyer . they hash out the fine details and come up with a sellers agreement everyone can live with .everyone signs that at closing  Atleast that’s how mine have went 

I'd obviously have a lawyer state it more eloquently than that and something that could hold up in court.  

I’d definitely ask a lawyer before signing letters or paperwork

You are looking for the "One to Four Family Residential Contract (Resale)"When you have a lawyer go through the contract with you, you should ask him/her about the process for recording the contract as well.

Tell them to talk to a lawyer and/or turn them over to you!

@Sam Nelson I am not a lawyer, but I think you can use a bit more scrutiny when looking for a roommate.

What I net depends on whether I involve anyone but my lawyer.  

Hire a lawyer and send a demand letter.

should i obtain a CPA and a lawyer before purchasing my first deal?

I did speak with my RE Lawyer who drew up the LLC and Operating Agreement and my CPA and both seemed to be comfortable with the approach e.g Solo 401k Trust Account owns 25% of the LLC.