Or would you come in one deal at a time over the next 3-6 months to be all in over 2-3 year period using same diversification goals (asset class and geography).  

A few metrics to help narrow down a submarket can be; population growth, rental growth, income growth, job growth, job diversification.

The units that I have leveraged could have 6 months of vacancy and still pay for themselves, and I have a mix of free & clear & leveraged (diversification!).

In stock investing there is "diversification."

Another consideration is that I also have many other of my assets in the stock market so this provides some nice diversification and I also hope to one day to get more invested in real estate and this helps me keep my foot in the water -- though I haven't had a chance to learn and do as much as I wanted to because of work/family obligations. 

It's good diversification. 

Items like job growth, rent growth, population growth, employment diversification, income growth can help identify market trends.

You need the same education to properly invest in real estate, some of which includes the legal aspect, the tax consequences from every angle you can imagine - things you haven't even thought of yet, the importance of diversification of your investments, etc.

A lot of individuals will also invest none retirement funds in real estate for diversification purposes.

Don’t buy huge multi – not enough diversification for you right now and also they are difficult to liquidate when you are ready.