Some very popular markets have stagnant or declining populations and virtually no job growth but they are popular because they are cheap.

probably not the most popular opinion but my personal belief is that saving the 20% is a waste of time. if it takes you a year to save up that much money the market could go up, interest rates could go up, you're missing out on tax breaks and the reality is you're going to be living in one side of the duplex and renting the other one out to cover 80% + of your mortgage.... kind of a no brainer in my eyes but everyone has their reasons.... if the numbers work, I don't worry about PMI

If the retail market is stronger and has few/no vacancies in the area, see what the vacant spaces are being marketed for, how long they have been on the market, and weight them as inferior, equal to, or better than your space. 

There are plenty of multifamily-based books and people have varying opinions on which ones are the best, so just find a couple popular ones and start with those.  

One of the more popular options is Podio.

Although, I would bet that 30-year is by far the most popular.

@Teho Kim Texas is crazy popular for investing right now.

@Seth Ferguson I agree that goals and interests must be aligned, but how much weight do you give to their experience level?

Uptown is so popular and in demand, even for non-students. 

https://www.cnbc.com/2018/06/13/u-s-cities-most-popular-for-millennials.html