As a realtor I have access to many listings.

Not a course, but I recommend the book "Crushing it in Apartments and Commercial Real Estate" by Brian H Murray.

For the purposes of property tax, they change formulas starting 4+ units to commercial models. 

Also, keep in mind that the DMV for vehicle tags is at a different location.If you love easy access to nature, you’ll love it here.

Commercial?

Tenant estoppel letters should be used in the sale or purchase of any tenant-occupied real estate, whether residential or commercial. 

In general, you're going to make more money on solid middle class flips but you're going to need access to more capital to get it done.

At various times during the past 25 years he “specialized” in oil and gas drilling, franchise sales, surgical center investments, office centers, start up incubators, vitamins, mobile washing equipment, cemetery syndications, residential mortgage brokerage, commercial mortgage brokerage, insurance as an investment, long term care insurance, and property development in Mexico.  

You'll also have access to the MLS, be able to do a lot of the work yourself, and save quite a bit on your first purchase. 

If you keep growing, you can also keep more of your capital working by having access to funds that may or may not be liquid cash.