Help with keeping Seller Financing deal organized/legal

[Michael Filipidis]

I have reached a deal with my neighbor in our townhome community to purchase his townhome with a 12 month seller financing deal! 

Price is 115k pending appraisal with 5% down. Owner has fully paid off the property. At the end of the 12 months, full remaining balance is due which I would then go to the bank across the street and get a mortgage. Not able to get a mortgage now since there is an HOA assessment on the townhome currently. Tenants next door are willing to sign a new lease with me at 1,200/month.

My main question is what do I need to do to keep everything legal when it comes to signing the seller financing deal and the property title/deed? All advice is loved!