Hopefully having 4-6 rental units will be enough to supplement my current income so I can retire early!

I am interested in learning more about real estate investing as I am ready to purchase multiple properties now and need to better understand what I am doing as this will be a supplement to our retirement income.

I own a home in Miami, and I'm currently in the process of closing on a condo in Homestead (an hour south of Miami.)I'm eager to invest in my 3rd deal, and mostly interested in multifamily units.The way I see it, I have two good options, either invest in the Midwest, I like Cleveland (for MFH) or Indianapolis (for SFH), or purchase a multifamily property somewhere in Norcal and relocating there for a year (Sacramento or Stockton, or possibly Fresno) using an FHA 3.5% loan.Ultimate goal is to buy and hold to supplement my retirement and I'm very glad to have found this community to learn and study from.

My main goal is to build a stream of cash flow to supplement my income and build wealth.

@Elizabeth V.If I might supplement @Jeff Rabinowitz's recommendation about directing strong applicants to upcoming rentals.  

I currently own one lonely investment property and am looking to buy and hold in order to supplement my retirement one day.

My wife just recently became a realtor and introduced the idea of supplementing our income through real estate investing.

My goals are somewhat ill-defined, in that I haven't narrowed in on what I would "need" to retire without a job, but in the essence of providing a benchmark for discussion purposes, let's say I would like to:- Generate system of cash flow w/in next 10 years to supplement overseas travel expenses and hobbies for family of 5.- Have enough wealth accumulated by age 45 to afford college tuition assistance for 1+ children- Stop ALL W-2 work at the age of 60- By age 60, have enough income through military retirement, cash flow, and other ROI to cover living expenses + leisure (travel, hobbies) for my wife and I; goal would be to have no mortgage on primary dwelling- Establish a trust worth a darn to my wife, children, grandchildren, etc.

To be honest, I want to supplement my income with real estate but I am also apprehensive. 

I supplement my income from a substitute teaching position that is on call.