I bought my first rental in graduate school at 23 (it was seller financed, although I could easily make the payments I doubt a bank would've ever approved me for a mortgage at that point as a bartender and Teachers assistant). 

@Brandon TurnerYou and David are great teachers.

However, I plan to be a teacher next year.

so you could get either  teachers/ nurses/ people that want to be closer to work or the town to fill your units and stay longer term than students so it would really be up to how you screen your tenants and what you setup.

My advice to you is action is your best teacher.

Chad is a good guy and natural teacher. 

Then, how to make the numbers work on my teacher salary. 

How do you tell the difference between a guru and a teacher?

I learned the note-taking trick from a school teacher who protects himself from any potential child/parent accusations with journals on each child.

(If these number sound ludicris, they're not, I legitimately know a teacher who has these exact numbers).