It's from 2016, so you may want to supplement it with some more current market info. 

I am retired so I want supplemental income and rentals gives me that without having to sell anything, by improving the properties and raising rents I am also increasing the value.

My definition of cash positive takes into account cap expense (high in San Diego: I use $250/month for attached normal rental size and $300/month for detached), vacancy, standard maintenance, and any other expenses (I have 2 units I pay water and trash, 3 units I supplement the water, and 3 units I pay a gardener).The market at its current price point versus rent is more of a property/rent appreciation play. 

I'm w/Bryan, hands on w/supplemental reading / courses, etc is a must.  

Supplementing with part-time work will certainly help.

I imagine that we would slowly sell off the properties and use the profits to supplement our monthly income until we hit typical  retirement age (when our 401ks and social security would kick in).Would appreciate any resources or advice on this!

It is for a supplement to retirement, or to build something for full time money.

Our goal is to secure enough properties that we can live off the cash flow or at least supplement our retirement.

Each of those special assessments should be listed on your property tax bill (or supplemental property tax bill).

If you're borrowing $1M to buy a 30 unit apartment, your networth has to be at least $1M or moreSo your only option at this point is to look for an experienced apartment investor who is willing to guarantee the debt as well as supplement your downpayment.I strongly advise for you to NOT raising capital from private investors at this point (without an experienced partner/ loan guarantor) because of your lack of a track record.