With $100k, focusing on properties that offer high rental demand or flipping potential could allow you to leverage your funds effectively, especially in your booming area. 

Internet chatter is a good starting point but most of my investors say the gold is going deal and taking relationships offline. 

Waiting too long to refinance can also leave you with less favorable market conditions.Neglecting to Build Relationships with Lenders:Many investors assume refinancing will be easy, but without building good relationships with lenders or shopping around for the best terms, you could end up with a deal that doesn’t work for your investment goals.Ignoring Cash Flow:Some investors get caught up in the equity gains and forget about cash flow.

Build your income and reserves, learn and build relationships.

When acquiring a large portfolio of rental properties, what strategies have you found effective for managing or dividing the properties?

Mixing business with personal relationships can get tricky, and you want to make sure you’re both aligned on your financial goals, expectations, and boundaries.

Seems you are new to this- you can get just as good protection by working with an agent or broker and will see more deals through developing that relationship. 

If you can self manage effectively, you will find good cash flow there.

What I wrote above does not create an attorney/client relationship between us.

It's easiest if the builder and the lender have an existing relationship.