So not looking to become some overnight millionaire just simply supplement my lifestyle and see what happens.

Umbrella insurance is supplemental to regular insurance.

A simple, low cost method...especially if it is only a problem for a few months out of the year...is window units (for heat or a/c) or baseboard heating, to help supplement the temperature provided by the HVAC.

Garage apartment we're renting on Airbnb actively managing all aspects to supplement monthly income and pay for home mortgage.

Depending on your area of interest there are some great books by J Scott and Brandon Turner that can be purchased on BP or Amazon as a supplement to reading in the forums.

I have money saved in a brokerage account doing okay with some mutual funds, want to start doing REI to supplement income and create possibilities.  

It was in perfect shape for an investor.Also I would not expect that the other tenants will cover the entire mortgage at least when initially purchased,  Their rent may supplement your rent such that you are paying below market rent. 

I am currently working in the Transportation Industry and I'm excited to get started in all aspects of REI to supplement my current income.  

Also, I've decided to get my real estate license for a couple reasons 1) to get access to the MLS 2) be able to look at properties and make offers myself and 3) supplemental my income.

Much like anything in real estate the numbers depend on how you purchase it (i.e. with using it for yourself as primary driver, or making money as a primary driver).If you’re looking to supplement the cost of ownership, but are buying for yourself maybe in all reality covering the mortgage is good enough for you.