Explaining the purpose of the contract to the seller

[Matt Beans]

Hey BP!! I have created a sellers list of vacant properties by driving around, but im a little apprehensive to send letters due to uncertainty. How do i explain what im doing with the property? Do i tell them im buying it? Or flipping it? Also, how do i explain gaining equitable rights without buying the property and why would a seller allow me to gain the equitable rights without paying them for their property? Thank you in advance for any clarity!