Method-wise it could be helpful to get a (lightweight) computer algebra software and learn how to use it and how to explore knowledge using it. One thing you won't have when you're out on your own is a method to just try out stuff and verify that it is correct, or to get better visualizations quickly. Often you will get stuck with something and need a different angle (which teachers or other students could normally provide). Then you can just open the software and play with it.
One place to do that for free on a basic level would be Wolfram Alpha: https://www.wolframalpha.com/examples/math/
Edit: (I mean this in addition to the learning resources like books and videos)