Rick's answer is spot on. Rent to own almost never works out in the tenants best interest. If you are able to buy then you should speak to an agent who can set you up with a solid lender. They will walk you through the pre-qualification process.
If you need to lease while your credit improves there are a lot of wonderful properties that you can look at. Keep in mind, while Rick states credit is an issue with renting as well, proof of income and a solid rental history are far more important.
If you have any questions I would be happy to walk you through your options. And don't ever pay an agent for their time. Commissions are built in to contracts that are paid on the sellers side 99 percent of the time. Don't get tricked and don't ever work with an agent that you don't feel has your best interest in mind.