Vacancies are the killer of cash flow.   

This could be the deal killer or it can get really expensive.Best of luck, 

Weeds still pop up but easy to pick or spray weed killer.

@Nicole CotrinoI am actively Investing in NJ specifically in Hudson county, and you are right that property taxes is a killer, although from what I heard from others definitely start locally or at least driving distance from were you are.And by the way if cash flow is your primary interest, then you can definitely find some area with decent cash flow although they are tough markets, off the top of my head Trenton is one such city.And I see you come from Toms River NJ , that market should skyrocket in the next 5 years with all the influx from Lakewood, you might not have a great cash flow, but long term appreciation should be a amazing.

The only advice I have is make sure you get a killer deal (20% below market) and you could probably make the area work.

You'll be running a business and property management can be high risk if you're not fully versed on the Fair Housing Act, have a killer lease contract and addendum ready to go, along with a solid application and screening process. 

@Patrick Murrayjust to take another run at this... you got some great and thoughtful feedback from @Joe Hammel and @Travis Biziorekto summarize: on market + already occupied + conventional financing = not possibleif you found an absolutely killer BRRRR deal, and screened and placed tenants yourself, is it possible? 

That would be a serious deal-killer around here.

Using a realtor to find an investment property seems counterintuitive because why wouldn't they keep the killer deals for themselves and pass the mediocre deals onto their best friends who have been making them money for years?!?

The usual problem I have found in these situations is the BF moves in afterward (so at least they are being honest and moving in together), and the BF has an exciting prior criminal background that is usually the deal killer.