RE: Vacant Boarded House/ Teardown

[Edwin W.]

Found a vacant boarded up house that is a potential teardown in a great neighborhood and in a competitive area. Lot size is about 7,000 square foot. Skip traced and found out the owner's tax mailing address. Also, through another online source, the property looks to be free and clear. Zestimate value is almost $700,000 and REDFIN has $600,000 as estimated value. Should I knock on the seller's door or drop off a Direct Mail piece at her front steps as first contact?  How much do I offer to the seller? Should I do an assignment of contract and wholesale it to a builder, or seller financing? I'm still new to the game and anything feedback would be appreciate it.