The answer to your question may be simple and I really think it's one that only you can answer, because only you know your risk tolerance, and only you can determine what your investment goals are.It may get simpler than that. 

Decide what your goals are, how much time you want to spend on it and what your risk tolerance is first.

You have to know who you are and your risk tolerance.   

This seems to depend on your personal risk tolerance and how much of a cash reserve you are starting with.4.

And risk reward tolerance's your finance's etc. 

If you don't, you need to keep a lid on things i.e. water saving toilets, landlord thermostats, keeping a close eye if tenants are having several other people live there, car washing services on premises, etc.In the end, it all depends on how it cash flows and your tolerance.

I am no expert in this but from what I have gathered listening to other posts on this site, it is very much dependent on what your risk tolerance is.

Personally if I have $40k profit set for a flip but after I run the numbers I see that I can pay a little more for the property and net a little less, that's all about your tolerance for risk.

Basically there are dozens of different ways to invest in real estate, and you have made absolutely no indication of your goals, your experience level, where or how you want to invest, or your tolerance for risk. 

Your higher your risk tolerance when it comes to leverage is rewarded by cash on cash, but the leverage works both ways.