Short sale vs. Pre forclosure

Hi all, I am looking to start in pre-forclosures. If I come accross a motivated seller? Is the idea to offer a contract, subject to existing financing?

And, what are the benefits of dealing with the bank in a short sale? Wouldn’t the short sale be subject to conventional financing?

I lack the strong credit to do a deal without owner financing. So what would be my best way to start in Real Estate Investing?