Hey Alexis, this is amazing that you're thinking about all of this at 20 - I'm jealous! Thinking about what I could tell my 20 year old self, my advice for you would be to start saving as much as possible. Don't sacrifice your whole life, you still should have fun and have experiences, but make it a priority to put money away every month into a high yield savings account. You could also start investing in online real estate platforms like Fundrise, but I would prioritize saving cash for your own real estate purchases. Then I would say build your credit responsibly. If you don't have a credit card, definitely get one. Go to your bank and ask them to sign up for a no or low annual fee starter card and use it wisely!
As far as getting into your own rental property, if I was back to being a 20 year old I would do anything possible to get myself a house-hack. Find a lender and work on getting a pre-approval, or have the lender give you an action plan to get to that point. You're in a stage of life where you might be living with roommates anyway, so find a property where you can rent out rooms and live there yourself.
If you're trying to work in real estate, that's another convo, but happy to chat about that as well!