It's all very easy to say that good management is the key but if an area has declining demographics it hits values and rents often so you have no exit strategy. 

Location, market supply and demographics can be factors.

Hell, there is this burgeoning website, census.gov, which provides essentially any element of demographic data one could ever imagine down to census tract block groups (which, in cities, is a very small, concentrated area). 

That's the demographic.

For example, if you are buying in an area that is predominantly Section 8 or almost every call you get about a rental is Section 8, then the decision may be made for you (based on markets, demographics, location of rental, etc).

I plan on targeting some different demographics and adding more marketing channels for the upcoming year, and I expect that to increase my deal flow, and help me to also reach my goal of doing deals more consistently rather than deals here and there.

To ID markers with both, look for both.At market level verify industry diversity,    review masterplans, ID path of growth, economic development incentives, top 10 major employers.Neighborhood level: crime rates, renter vs owner ratio, average income, major employers, vacancy rates, units under construction, quality and type of closest retail, demographics, community tapestry ESRI, most common household formation, etc.There are also things you should be looking at in the subdivision or block the property is located on (ex. renters vs owners, developer and quality and age of housing, ideal housing for your target tenant, etc), but again the things you look for should be based on your specific goals, investment strategy, and investment criteria.

Obviously this is an over simplified example and many factors would go into reducing vacancy rates, but the core reasoning is that if your market is young professionals, that demographic places a higher value on certain features.Personally, I am in agreement with @Alexander Felice (great name by the way, people named Alex are usually pretty awesome).

I'm hoping for a 3/2 brick because I think those can sell easily within a certain demographic in my area, and because with the brick I'll have fewer termite issues to worry about.  

Look at the demographics, crime rates, typical rents, and home values.