Accidental Landlord and Newbie Investor - Advice welcomed

Happy New Year BP Community!

I am a lawyer by trade but a budding real estate investor since I inherited my childhood home (no Mortgage) in Fayetteville, NC and I finally have it fixed up and ready for rent. I am discovering Bigger Pockets and hearing a lot about BRRR and pulling out your cash in a refi. Since I have no mortgage and I would love to recoup my out of pocket expenses, is a HELOC a good solution before I get a tenant in there?

My husband and I also own a vacant lot next door to our home in Charlotte and dream of building a duplex with an accessible dwelling unit in the back to rent out and take our door count from 1 to 4 and the HELOC on the Fayetteville home would be a nice head start on that project. We have never developed a property before though and would be new to the construction loan/financing piece to see it through.

Any and all tips and suggestions, caveats and warnings are welcome and appreciated. Thanks in advance.