I think you have received good advice. Pay off loans and purchase a duplex. One thing to be careful of, though, is justifying too large a purchase because it's an "investment" or because your tenants will be paying much of your mortgage payment, for you. That may happen, and I hope it does, but it may not work that way 100% of the time.
Pick a reasonable duplex, ideally, one that you can afford to cover the entire mortgage, if needed. This is your first step into this world, this is when you are most likely to make mistakes, so make them small mistakes.
When I purchased my first rental home (which I still own), I payed $28k for it. The reasons for that were 1. it's all I could afford 2. if the Sh*t hit the fan I could afford the $150 mortgage payment. 3. If I was going to make a mistake I wanted it to be a small one.
Turns out that one wasnt a mistake. I decided to make my mistakes on later purchases.
Good luck man, I hope you have much success.