With this method, you really have to be disciplined and very careful.

You debt to income ratio is the test of if you can be disciplined and live according your means AND save. 

If we find that they're disciplined and have a good work ethic, we'll have one of the other day laborers teach them additional trades.

The key as an investor is to stay disciplined and stick to your plan.For the real estate market, I believe we are in the "wall of worry" stage.

If you have the discipline to follow everything else he recommends, you won't get yourself in a bind by overextending yourself with debt.

If you have borrowed money at a high interest rate (perhaps with a balloon payoff in the not-too-distant future), you need to attack this thing VERY differently than if you are buying it with a cheap conventional loan and you'll be living in it.In either case, be disciplined about your scope. 

Using one's good credit and W2 income to get bank's unsecured credit lines is cool but as you said, treat it with discipline and with caution.

It is not the amount that counts it's the discipline.

The advantage to this is that the property will either cover most of your living expenses or potentially all of them (better chance with 4 family).Either way, your financing will be based on owner occupant financing rather than investment financing where you're required to have a larger down payment (25-30%)and will pay a higher interest (usually 1-1.5% higher than owner occupant).Going in this direction will allow you to grow quicker since you can save what you would normally have been in rent and thus get you to the next property faster (as long as you don't spend it...discipline is key).Travon, It is possible to finance a second property while still paying for the first. usually, banks will give you a 75% credit on collected rents (make sure to have signed leases).

But knowing me, I'll likely end up using it for another acquisition (I'll try to be disciplined though!)