I think you've got a bad book there. "Big Money" right there in the title? What does that tell you? It tells me the book is targeted toward people who 1) don't have money and 2) want a lot of it. If there is one thing I distrust, its books targeted to an audience that 1) doesn't have money and 2) wants a lot of it.
It is my opinion that the reason Dave Ramsey and others stress having (at the very least) 20% down for a home is to show that you have already put some effort into the deal. Really, if you can't buy an investment property outright, chances are you can't afford it. I've seen several threads here that advocate borrowing money to finance things at a lower rate and invest money at a higher return. Its great on paper, and if you've got the liquidity to cover the shit life throws at you, then perhaps it even makes sense. However, if you /need/ to borrow money to make a deal happen, then you've got a problem. What happens when things break, your tenants move out, the market fluctuates widely etc? These high % financing gimmicks let people get themselves into situations that they can't really afford. Ultimately, you'll be left with the responsibility for the mortgages. Don't let the desire to build your portfolio quickly jeopardize everything when things don't go according to plan.
Yes, I am very risk adverse.
Disclaimer: I feel its only fair to mention that I don't have any experience with these things. I'm about to graduate from college and start my life. Its just I have a real passion for finance so I've been reading up on it for a couple of years. I figure its best to do a ton a research ahead of time and get several perspectives before you get stuck in something with serious repercussions...