The problem with "rent to own" is that everybody means something a little different by it.  Here are some examples of what someone might mean when they are talking about a "rent to own" scenario:

1. Owner won't sell the home to anyone without checking with the tenant first to see if they want to buy it (first right of refusal)
   
2. Owner and tenant decide on a sale price for the home at the start of the lease, and the tenant has the right to buy the the home for that given price at some future date.
3. A portion (or all??) of each rental payment will be credited back to the purchaser if and when they buy the property.
4. Tenant pays a large nonrefundable deposit at the start of the lease, which is credited back to them in its entirety if they purchase the home.
   
5. Any combination of the scenarios above, for example no fixed price is set, but a portion of each rental payment will go towards the eventual purchase price.

If a landlord and tenant are both generally interested in pursuing a rent to own scenario, the first thing to talk about is what each party means by "rent to own."  It can be a win-win situation for property owner and tenant/buyer, but you'll need to first make sure everyone is on the same page.