Start gathering a few popular science books on subjects directly on and also near to your goal. Some people reject popular science books as too light weight, but it does have value. This exposes you to the variety of subjects in and around your interest. You might not have been aware of some aspects of your topic and you are introduced to them here without too much effort. You also learn to associate detailed technical topics to the wider areas where they are used.
Read the whole book. Books are better than random google searches and videos because they will guide you into areas you might not have considered relevant. Broadening your base knowledge will allow you to make a more informed decision about your favorite topics. Once you have a broader and more informed understanding of the topics and areas involved, you are better able to identify your interests, or even switch interests.
That is when you start going into a more detailed dive into your target topic. Follow through and read the whole thing. Again, pick one or more text books or deeper science books. The purpose again is to guide you into areas you might not have considered before.
This time, you will hit lots of technical subjects that you might not know. That is when you go searching for online information, wikipedia, online course videos, Youtube content or other textbooks. For these, you will only need to cover enough to support your primary interest, and you will have a fairly good idea how much that is.
You are not going to go professional with this, but it will be more than enough to keep your interest up and curiosity satisfied.