Buy solid appreciating stocks.  

Is it to give up the 9-5 or you 're looking to diversify from Elon Zuckerberg stock management portfolio.

I don't use those so I can't comment on them, but the principle is the same. 

I do not have much knowledge on real estate but I am the hitting  books: BRRRR by David Greene, Estimating Rehab cost by J.Scott, Investing real estate with no/low money down by Brandon Turner and finally, Rental property investing by Brandon Turner.Outside of real estate, I enjoy swimming, bike riding, watching anime, playing video games and interests in the stock/house market.Excited to learn and connect with you all!

I was wondering if I should use my salary to pay off the mortgage loan so I don't have to pay too much of the interest Or let the tenants pay my mortgages over the 30 years and use my salary to invest in other ventures such as ETFs, stocks or buy more houses.

It’s never truly passive, you can’t just set and forget the way you can in the stock market

I have lots of saving in stocks.

We utilize an engineering department and do a LOT of analysis to ensure our insureds are adequately protected while also pleasing our broker(s).I studied finance in college and would confidently say I'm ahead of the curve in equity investing (stocks).

It is also a low-risk way to learn all the principles of real estate investing with very limited risk, gain experience with evaluating, buying, repairing, renting and managing a property.

This is no different than picking a high risk stock and the stock goes bust..