In most single family zoned areas adding a single ADU is not a value add meaning it will not add more value than the hands off cost of the addition.  

My goal is to acquire my first investment property, ideally a single-family rental, by early-2025.I’m particularly interested in hearing from others who’ve navigated the Hudson Valley or Catskills markets, especially with rental properties or creative financing strategies.

When you have a duplex and tenants on both sides stay for ten years, it almost guarantees that something isn't right.I would study your market and determine the value of your rental, because I bet you are losing money every month.

I have one single family near a hospital and am in the market for my first multi family.  

AirBNB is a platform.Personally I like a single, eye catching line.

I’m hoping to find more success in Phoenix, but as you stated, the old fashioned way may be my best bet.

Focus on analyzing properties and starting small, like house hacking or buying a single-family home to rent out rooms, while ensuring cash flow and maintaining an emergency fund.

What has worked for me is duplexes and single family homes. 

., "I will buy at least one single-family home, duplex, triplex, or fourplex before the end of 2019") and then do it.

FWIW, I'm going to base this off a 1,500 SF single family new build, but I'll predict the build cost will be a little over $200/SF.