Reviewing my own criteria, I guess I would have to say I use a combination of Aaron & Nathan's method.

There's got to be a more precise method, I'm sure?

@Edwin Brown I am in the process of making an offer using this method.

It is a great source of passive income.I recommend books and audio tapes found at www.jimmynapier.com on the subject of buying debt as a great way to become better acquainted with the business and how to get started.What may the best method for you to begin is to become an investor with a developer.

My question is, is it impossible to change the method of acquisition when already under contract?

While the methods described about are great and increase convenience, they fall short of some options available. erentpayments allows it (one of the options you can select) and clearnow does it as well.

Find Brandon's videos on YouTube for the "four square" method of analyzing homes and practice.

But you're approaching this methodically and should have no problem. 

This method allows you to reuse the same capital.

@Billy Smith that’s definitely one method I’m trying at the moment.