If you have some money in the bank to cover unexpected circumstances (vacancy/repairs, etc.) and you know that you're going to struggle to put together the down payment for a multi-family, then beginning to build up some equity, experience and momentum (by taking action) isn't the worst idea.   

While it can be tempting to jump right in, the best thing you can do is build up an emergency fund FIRST and then start working towards securing a property.I do this by working two jobs, may not be the most exciting thing to hear but hustling for a few years to achieve financial freedom in the future is worth it.

So if it comes to starting out like you said, I do believe single family 1-4 units is the way to go until they can eventually build up to get to multi family. 

Or is it to build up our “estate”, i.e., “net worth”, in the best risk adjusted manner possible? 

I think it takes some time to build up the relationship with your rep and get your first booking but seems like it's definitely worth the investment!

@Alexander RodriguezI have a tenant which always seems to get mold buildup in her bathroom.

3) While your building your deal pipeline, do what you can to build up your cash reserves and personal cash flow.

I've also considered investing in property outside of NYC, but it's more intimidating and I'm not even sure I should be one doing that, as I'm relatively young (28), not wealthy at all, not married, and am just beginning to build up my savings. 

The lot is steep and we had an architectural engineer outline how the cost to remove boulders and build up high (where there would be a better view) would be quite substantial but building lower by the road was more feasible.

Here;s the key : Postion your investments in real property so that the investments can take advantage of ALL of the following: 1- cash flow 2- equity build up through loan amortization3- price appreciation4- tax benefitsThe LEAST important of the 4 above are tax benefits as investing through a retirement fund, ESPECIALLY ROTH, will provide tax shelter itself.