Unlike traditional residential real estate mortgages, real estate investment financing is way more creative and offers more options than you think. The golden rule in real estate investment is OPM (Other People’s Money).I have enough money; shouldn’t I buy my real estate investment for cash? No, I absolutely advice against investing large sums of cash into a single real estate investment. There are two reasons why not. First, you give away most of your profits by not leveraging your real estate .