If you are just starting off and are somewhat new you might want to consider "strong business credit" this will enable you to build your businesses credit to attract more traditional lenders.

I get lots of such supplemental property tax bills.  

I am interested, as of right now, in either single family or multifamily investing.Currently my basic real estate investing goals are meager, supplement my current salary with passive income from rentals.

Then, he/she will be able to help you construct a plan that will enable you to reach your short-term goals and reap the benefits needed for the proceeds and resources that your long-term goals will require.

I hope to acquire enough properties to supplement enough pay in rental income to leave my job to pursue flipping options or further rental possibilities.

Is there anything I can do right now or within a year to supplement my income to leave my job?

Same idea, trying to push investors out, and to enable owner occupieds to compete. 

I do not have building expertise, however am connected with a great builder who has those skill sets, so we combine our experience enabling us to embark on and execute projects we otherwise could not do well on our own.

My main goal is to supplement my retirement income with $5K in passive income.  

I would like to start with a few wholesales or flips and then grow a portfolio that enables my money to work for me...instead of me working for the money!