Hi Mark,
Welcome! There is a wealth of info here and I only wish this place existed when I Was cutting my teeth getting into multi family investing New Jersey!! :)
To better answer your question I think the answer depends a bit on what you want and your comfort zone, also the rate of return you are willing to accept....
I have been investing in Union county and Somerset county. I use to live in Union county and began acquiring properties that were in my backyard so to speak as I was very familiar with the market and what I can rent these properties for. The other thing which is huge to me as I self manage, is being in close proximity of my properties as the thought of managing something far away does not sit well with me and I prefer to self manage VS give to a management company.....
NJ is a tougher state by default to invest in and generate good returns due to very high taxes and high price points on properties but along with this comes fantastic rental income if you buy the right property and buy it at the right price.....
Don't let that discourage you it definitely can be done. I have a portfolio of multi families, single families and condos all of which produce great cash on cash returns.
Where do you live? Do you know the market in your immediate general area? When I first started out I bought a Mother/Daughter - very similar to a 2 family and lived in 1 unit and rented out the 2nd unit... My tenant paid 3/4 of my mortgage and I thought I was a 22 year old genius!!! lol This allowed me to bank a fair amount of cash and but something else and I was off to the races!!
(EDIT) Just saw you were from Teaneck, that is Bergan county right? my mom has family up that way, nice area!!
regards,
Chris