Expect rates to be higher than "typical" financing programs - right now, I'd plan for at least 8%+ depending on the whole scenario. 

It generally isn't worth the brain damage of experimenting though....especially if you want to move to a new home that you will own inside of the typical lender's seasoning period.

If this is not something you're interested in delving into and learning to a high degree, then investing in publicly traded REITs would be another good option for you, which have historically returned about 13.5 per cent Per year over the past 50 years (1977-present), beating the US stock market by two per cent and even beating private real estate investing by 4 per cent (that's compared with the average real estate investor, not the experts here at Bigger Pockets).

I started with single-family homes and then moved on to condos, typically holding onto properties longer than I probably should.

.: I would go HELOC for sure that would be best as others were saying the lower cost for the money changes between paying a higher rate for a personal line and typically personal lines they want a higher monthly charge as well independent from the interest rate.  

Master Lease with Option. 

Having only the guarantor screened and closing in an LLC are options. 

What is the typical minimum investment requirement?

Business loans typically won't let you purchase a property if you read the fine print.

Hard money and private investing are both ways to finance flips, but they work a little differently.Hard money loans are typically from companies or private lenders that specialize in short-term, high-interest loans.