The experience will be invaluable for flipping.Learn to live a frugal lifestyle, save every penny and surround yourself with like minded individuals.Do not get into the modern day habit of living for today, pay check to pay check. 

@Eran Greenburg It is a question on habit and how deep the details are really needed.

And if the value of your assets falls, as real estate has a habit of doing, and you have loans on that, you can easily end up where there is little or even negative equity.  

@Komal Patel this is where knowing you market is vital.

@David Dachtera good points - thanks for chiming in.One point I found interesting was one made at the end of the article, regarding the real estate purchasing habits of millennials.  

For me the first thing I needed to change was my spending habits, and control and understand exactly where every dollar I spent went.

I didn't like charging the late fee, I debated not charging it, but was concerned that if I didn't enforce the late fee clause the tenant might get in the habit of paying late.  

It makes sense to me to start with a standard contract, put these vital items in there.  

(A) A landlord who is a party to a rental agreement shall do all of the following:(1) Comply with the requirements of all applicable building, housing, health, and safety codes that materially affect health and safety;(2) Make all repairs and do whatever is reasonably necessary to put and keep the premises in a fit and habitable condition;(3) Keep all common areas of the premises in a safe and sanitary condition;(4) Maintain in good and safe working order and condition all electrical, plumbing, sanitary, heating, ventilating, and air conditioning fixtures and appliances, and elevators, supplied or required to be supplied by the landlord;(5) When the landlord is a party to any rental agreements that cover four or more dwelling units in the same structure, provide and maintain appropriate receptacles for the removal of ashes, garbage, rubbish, and other waste incidental to the occupancy of a dwelling unit, and arrange for their removal;(6) Supply running water, reasonable amounts of hot water, and reasonable heat at all times, except where the building that includes the dwelling unit is not required by law to be equipped for that purpose, or the dwelling unit is so constructed that heat or hot water is generated by an installation within the exclusive control of the tenant and supplied by a direct public utility connection;(7) Not abuse the right of access conferred by division (B) of section 5321.05 of the Revised Code;(8) Except in the case of emergency or if it is impracticable to do so, give the tenant reasonable notice of the landlord's intent to enter and enter only at reasonable times.

What about the vacant units...are they habitable?