This seems like something that should not be too difficult to do, especially as an owner/occupier. 

But your tenants may be less favorable than the tenants in better neighborhood, making property management more difficult. 

How difficult it is to do better this way over using a turnkey company and how much effort on your part will depend on the market and your timing.  

Not impossible but would be difficult. 

Insulation and ventilation is the other answer,  however these solutions can be very difficult and expensive.  

small deals are very difficult for investors.. because as stated if something goes wrong the cost of collection could exceed the investment.. rip it off of a credit card.  

We do have a 0% down mortgage program for first time resident buyers (that can only be used once), but the property purchase limit is $200,000 and it is difficult to find multi-unit properties in this price range - unless they are in a C or even D area.

Retiring young is difficult because the "freedom number" is unlikely to stay static.  

Everyone tells me the market is a sellers market these days so good deals are difficult.  

It may be extremely difficult to collect from them if they end up owing you money.