The first thing that needs to occur once you find a Buyer who will enter into a Leaseback contract with you is to negotiate the Purchase Price and the Rental terms.
The investor who buys your house is approaching it as a business and will be looking for a financial benefit or return on their investment. They will calculate the overall cost of acquiring and maintaining the property and determine the monthly rent to achieve their goal. They will present you with an offer that includes the Purchase Price and how much rent you will pay and if it is acceptable you move forward to a closing and sign a lease. Normally when you sell your house you rarely have any further interaction with the buyer after the closing. The unique thing about a Leaseback is that it is the beginning of the relationship, not the end.