Tenant wants to rent to own Chicago SFR--How do I structure this deal?

[Kimberly Land]

(This question can go into so many forums but I'm choosing this one because I need advice on an RE deal.  If I'm in the wrong forum, let me know, please)

My tenant wants to purchase the house they're renting.  They asked for a rent to own option to settle within the next 2 years.  I've never done this.  I'm certainly open to it if the numbers are right.  

Any thoughts? How do I structure a rent to own deal?

Details:

Chicago SFR-south side; 4 bed/2 bath; 1900 sq feet; 2 car garage; double lot, corner; has about $15k equity. I'm earning $700/month cash flow after PITI. I'm open to selling so I that I can use the money to purchase more property.

Tenant has been there almost 2 months and loves it. She is always calling and asking if she can make repairs and updates (good ideas for repairs and updates, btw), but she wants to pay for them so she can install high-end appliances, cabinetry, etc (and she knows I'm only paying for what works and is safe, not high end). This is why she wants to purchase the house-so she can make it a home.  Anyway, She says she is tired of moving her family every year; She wants to settle. 

How do I make the rent to own option beneficial for both of us???