Welcome @Claudia Frank! This is a great community, like JD mentioned, peruse the blogs and forums to get an idea of what people are discussing and see if that interests you.
I would also recommend attending local real estate networking meetups, reaching out to local investors, connecting with investors online, send them messages, ask to jump on a quick 15 minute call. BP, FB groups, Meetup App are all good places for that. You have a lot of options with technology but I would start with local meetups if you can find one.
If you want to invest out of state, connect with investors that do the same thing and learn how they do it and which markets and why. As you talk to a couple of people, you will get a better sense and recognize the pattern to it all which is find a good trusted team on the ground (agent, loan officer, handyman, property manager).
The agent will ideally help you learn the neighborhood, the good and less desirable parts of the city that you are looking into and help you find the home you are looking towards. You can do that in Oklahoma if you wish.
You will also recognize that there are a ton of strategies in real estate (fix and flip, LTR, STR, MTR, room rentals, etc). Take your time and learn a couple of them so you can add them to your tool belt of how to best invest for YOU.
Hope that was a good brief overview of what's to come! Excited for you and congrats on already having 3 rental units!