Quick answer seems obvious - work on increasing financial intelligence and buy another property.Ok, so buy another property - sounds good!

I know him to be a very good man and a very intelligent man.

Also, 4% doesn't sound absurd if you are talking about a small property with a relatively modest purchase price....if its a Million dollar property, I'd start to suspect they are artificially high. 

Yeah, in theory, market rent may not have changed... but those prices are artificial.

Just your hard work and intelligence in following these steps wisely. 

@Sami Gren call a new lender and see if they can match or beat your current rate, they might as interest rates have dropped recently, don't give yourself an artificial deadline to "keep your rate"  It takes as long as it takes to get the results and if they come back with contamination it can be very expensive to clean up.

Some books I would recommend - What Every Real Estate Investor Needs to Know About Cash Flow, Think and Grow Rich, and The Intelligent Investor.

I know this wouldn't be considered intelligent, but how many people have had experience with instead of paying certain bills on time, using that money to invest into/build their wholesaling business while their in the beginner stage of actually rolling out the marketing and building relationships at meetups, etc.

With supply chains being cut left and right all over the world, escalating quarantines, reasonably intelligent tradesmen who have better things to do than run out to job sites all day and expose themselves to infection or any sort of injury that involves going to the disease-ridden hospitals.But you honestly think that in this deal, you should worry more about housing value changes, bank rates, and what your hypothetical new tenants will be able to afford.It boggles the mind.

For 2 to 4 (or SFH) you can learn that from the "Education" Links above.As far as a job goes, it's intelligent to get the best paying (stable paying) job that you can and live within your means and save up as much as you can as fast as you can.For that read "rich Dad Poor Dad" (it's an easy 8th grade read).Good Luck!