This requires much more than you think. You need Property Management unless you're a handyman and have clones of yourself you can do major repairs at the same time with. You need a "power team" which is comprised of a legal representative, contacts for the renters, and so on. All of those things require time from you, so good luck working a job at the same time unless you outsource. Then your personal cash flow from the properties will be severely impacted.
RE: How to retire as a millionaire