Neighbor wants to buy house. What steps should I take?

[Quan Tran]

Good evening everyone,

I recently purchased a 3 family house in Massachusetts and moved into the first floor living rent free.  I also have a single house that I'm renting out, and after living rent free for a year, I feel like I've been missing out on all the savings these past years that I could potentially use to invest.  Therefore, after a few discussions with the wife, we decided that we will sell the single house and use that money to buy a few more multi-family in the next 2 to 3 years utilizing the profit.  Anyhow, my neighbor, who is right next door, wants to buy the house which potentially saves me a lot of money because I don't have to go through an agency.  My question is, how do I go about giving them a price, going through the due diligent paper works etc. Any valuable suggestions from experienced investors would greatly be appreciated.