A 401k loan has some risks...get layed off and have to pay it back or pay the 10% early penalty as well as income taxes if you cannot.A self-directed IRA is the typical retirement savings vehicle to invest in RE but it has undesireable attributes too.If you are young, you could diversify internationally or dip a little into emerging markets....they are not as highly valued.

Threatening to sue me for something frivolous will get the tenant on my undesired list and has yet to result in an actual suit. 

If I raise the rents, I might run into the unfortunate situation of having high turn over within a short time and that will put me in an undesirable financial situation,especially when I am pouring in large amounts of cash into rehab. 

@Charmaine M. marked rembert does raid some good points but for a buy and hold if you wait and search for the right deal you could do very will in Jamaica even south ozone park simply because I remember before I moved out of nyc I had friends living in what was affordable but undesirable areas like bush wick east New York and Canarsie....

Does anyone have recommendations for neighborhoods within NYC or close-by New Jersey that are a combination of affordable but not totally undesirable?

Otherwise, you'll likely want to have them split so that you can deflect the costs of electricity, water+sewer, etc. to your tenants.7) Agreed that 12% might be a bit much for a property manager, although if the property is in an undesirable area, you may have to pay more than usual to attract a top-quality PM. 

I prefer month to month, it makes it easier for me to get rid of undesirable renters faster, and I don't mind people leaving with 30 day notice if they don't want to be there as they may become a disgruntled indentured tenant.However yearly leases may make more sense in seasonal markets, areas of low demand, and when your rent is at or above market.

I.e. the area will become undesirable, rents will go down, etc.

Now, you have cheaper properties, undesirable that don't contribute to a tax base and could well be that they will have more in expenses as well as liabilities exceeding the taxes received.

I read somewhere that it is often undesirable to deal with properties represented by a broker when wholesaling.