Planning to use HELOC of first property to buy Duplex as house hacking

[Karan More]

Hey Guys,
I am new so still in learning phase. Planning to take out HELOC from my 1st property where I stay and using that to buy Duplex. Going to use house hacking and stay there to rent out other part. So going to rent out my 1st property as well. My question are:
-What are the things to do for making duplex good for cash out refi? 
-Which are key points appraisal look while calculating for cash out refi?
-How do guys work around duplex to get as much as cash flow?

I know CT properties are not much appreciating are in terms of duplex, so going to see as it as CF opportunity.
Any suggestions would help for sure.