Buying Foreclosures Sub2

When buying a foreclosure Sub2 first off has this been a success with anyone on board. Second what contracts could be used to do this legally. Im assuming a purchase contract, assigment contract or the two togethor residential with option to purcahse? My goal is to purchase the home sub2 then find a tenant to Rent to own with a two year option. Possibly giving the homeowner a chunk at the closing for allowing me to lease their home. Im in Florida