As far as the other property, my ultimate desire is to build a duplex for rent. 

After researching online I found landlord responsibility under California Civil Code section 1941 described as followsClean and sanitary buildings, grounds and appurtenances (for example, a garden or adetached garage) which are free from debris, filth, rubbish, garbage, rodents andvermin. 

The more relationships and marketing channels you build will only benefit you in the long run.

I'm a builder in Charlotte NC area and have been building 1300-1400 sq ft homes for the past 3 years.

@Gregg Scott I believe it is incorrect to say that income from a heloc is never tax deductible.  

The Columbus macroeconomics is booming due to many companies building out here like Intel, Meta, Google, Amazon, etc., and there is continuous population and job growth!

What strategies should I employ to build a professional network within the real estate community?

The ultimate tax-free transfer would be to inherit the property at a stepped-up basis.  

Just my opinion.Bethesda’s Clark Building Sells For $30M, 22% Of Its 2019 Price (bisnow.com)West Loop Landmark In Shadow Of Willis Tower Sells For Nearly 90% Discount (bisnow.com)Blackstone’s Defaulted NYC Office Loan for Sale at 50% Discount - Bloomberg

Quote from @Richie Linnon: I don't recommend small increases over a long period of time because it increases the chance of mistakes, it may still build animosity with the tenant, and the tenant may eventually reach a point where he can no longer afford the increases and he will leave.