Hi everyone!

I am new to real estate investment, but currently have two properties that I would like to turn into assets and start growing my portfolio. I am seeking feedback on what someone more experienced would do in my situation.

Property 1: Condo

• Rented for 10 years
• Negative cash flow of $300 (HOA fees)
• Loan balance: $30,000 / 5.25% APR
• Estimated equity: Approximately $100,000 based on recent property sales

Property 2: Single-family (Primary residence)

• Purchased in 2017 / 2.5% APR
• Loan balance: $230,000
• Estimated equity: Around $250,000 based on recent property sales

A little about my "wealth", my credit score is in the 800s, I currently have $50,000 in stocks/crypto and your typical Roth, 401k. My goal is to purchase an apartment building or a few multifamily properties for long-term or short-term rentals. I also have connected with another investor that is willing to invest 50k if the re-payment is favorable. 

Now, this is where I need some guidance: I am contemplating whether I should use my stocks to pay down the condo. Once it's paid off, I would have a positive cash flow of approximately $300-$400/month, (after taxes, insurance, hoa, water utility)

On the other hand, I could withdraw money from my stocks or take a HELOC against either or both properties and use the funds to purchase a multifamily property or as a down payment for an apartment building. I also have a couple of credit cards that have plenty of credit with zero interest.
In a perfect scenario I would use the condo as a collateral, no down payment. Has anyone done this before??

I am looking to learn!! assemble a team, lender, real estate agent, CPA, and build a network or find a mentor. Finally, I want to focus in multi-families in Texas, North Carolina, Colorado and Tennessee.

I appreciate any advice or suggestions you can provide. Thank you in advance.