Taking out heloc loan prior to renting primary residence?

[J Blades]

Hey Everyone, first time poster, I have a question about refinancing my current mortgage with the equity in the house.

Our family is expanding again sooner then later so we're going to purchase a new home. We've been actively looking for the past month or so. Our current house is up to date with with the major stuff furnace, roof, water tank. This will be our second rental, first one here in Denver. We have a nice house emergency fund in place there and I'm handy enough to tackle tasks as we'll be moving nearby.  Based on the market we're in the plan is to rent our current property and hold on to that long term equity. For renting we're looking at a rough profit of $600-700 a month. Currently based on what we owe and what the house is worth in the current market we have  $100k in equity on the conservative side.

Before we purchase the new property, is there anything I should do with our current property in terms of loans / refinancing or even taking equity out to throw at the new property some help with the downpayment? I was thinking it would be smart to take out a heloc loan to have the equity available just in case. 

Any insight is appreciated here as I have no clue about the financial stuff that should or shouldn't be done.

Cheers