@Benjamin Carver - I think that this is a neighborhood by neighborhood discussion ... so much changes between zip codes.

I prefer to look at the census tract level (and sometimes block level) as zip codes can be too large of an area to understand a sub-neighborhood's chance of success.  

Sometimes in the heat of the summertime you will see them wearing snorkel parkas zipped all the way up with the hood on.

I am now ready for my second property and I have seen a potential in the 89183 zip code of Las Vegas, NV. 

Close to 38117 which is a premium zip code. 38119 is one of the safer zip codes in Memphis.

My suggestion to you, after expanding your area, is to look up the zip codes.

There are some serious monsters or concentration of them in the 48204 and 48206 zip codes like on Calvert St, Tuxedo St, Lasalle, etc.

Areas like Murray Hill and surrounding (zip codes 32205 and 32210), Springfield (zip code 32206), and Arlington (zip codes 32211 and 32277) still have properties come up offering good cash flow. 

Doing 100 deals in the past two years is still almost no experience at all, zip, notta, it's not a determining factor as to knowledge, education, compliance, as it totally depends on what is being advised.

Those zip codes are close to Baylor Medical Center.