You must find a model where a purchase price will yield a certain amount of rent back, that will enable you make money for your needs. 

We encourage our students to look for neighborhoods where people like cops, firefighters, plumbers, electricians, teachers, secretaries, and other blue collar or not-so-well-paid white collar workers live. 

We will build a portfolio of buy-and-hold properties that will both cash flow well enough to get us out of the rat race, and appreciate over time.We will start our journey by house hacking a four-plex in Visalia that will enable us to put more of Eric’s retirement income towards real estate activities.We stumbled upon BP while learning about passive income.

My family had to cancel Spring Vacation trip ( Wife is a Teacher) at some monetary loss to accomedate the beginning of this project.  

Buy or inherit and hold all their lives while working the properties for income.I've seen teachers, firemen, software engineers and all sorts of people utilize both strategies successfully.

If you buy a duplex, you can apparently count part of the actual/potential rent from the other side right out the gate to increase the income you can show on your loan application for that first property, which can qualify you for a higher loan amount (thus enabling you to buy a larger duplex or in a nicer neighbourhood).

I'm a teacher/freelance writer and he's a doctor (Chinese doctors are NOT well paid like their American counterparts!

Great to take the plunge there is not better teacher than the mistakes you will inevitably make and come back stronger from on the first properties. 

Is not knowing a good excuse if you are the teacher?

I would recommend that you take some basic real estate classes to learn the laws of your state, but other than that I would surf around on forums like this and go to your local REI club.The best teacher is still experience.