Also if it is intended to possibly be a rental you should calculate the end result of the acquisition, the debt service, the rehab, etc and pretend to get a loan to refinance. then look at the potential rent to offset that monthly cost and see if it would cash flow.

Review their online financials/annual statements.

Strictly analytical speaking you cannot make a financial case for unleveraged investing in real estate.

The second habit that has helped me track my finances is that I’ve created a personal spreadsheet that I fill out at least once a month that tracks certain financial metrics I’m interested in comparing.

I don't have the time or the financial means at the moment for that.

If you buy the right property in Mexico, you can get a higher return by paying cash than if you buy a property with a mortgage in the US, especially right now and you don't have any debt.

It seems like your ROI is basically the same in each option, but you are taking on a much bigger project to convert a single family to a four-family.So basic calculations, since we don't have a full financial picture, i.e. what does financing of each look like?  

Long story short, I am in a bad financial condition as of recently.

So now instead of feeding the hungry stock market you can feed the hungry rental.I have watched people keep big debt on their home and then have the stock market crash.

You can sell on financial method because there is such short demand there is all but no comp's to use for comp method, and if selling as turn-key, yup, financial method will be your friend for sure.