Poppy42 has it absolutely right - "just getting started with self defense" implies a blank sheet. Mindset in my view is significantly more important in the beginning than marksmanship or physical ability to fight, in short it is the will to think tactically. Jeff Cooper wrote a very simple pamphlet, "The Principles of Personal Defense" (
https://www.amazon.com/Principles-Personal-Defense-Jeff-Cooper/dp/1581604955) which is fantastic in its brevity and gets right to the point. It is not about shooting or fighting, but about mindset.
To answer your question above, generally most people become familiar with firearms from friends and family members. If you know experienced shooters most are more than happy to share what they know. The advantage you get with this approach is that its cheap and the initial part of basic gun handling and operation can take some time to work through. The negative may be that the person providing the initial training starts you off with bad habits. After getting familiar, I would recommend formalized training. It is clearly a good thing and will take you to the next level. There is no substitute - perfect practice makes perfect.
If you have the inclination and the *realistic* physical ability to fight off a criminal predator, courses in Krav Magra or something similar is a good idea. Keep in mind, most criminals are young, male, often on drugs and physically capable. I am a small giant at 6'6" and have no plans to go hand to hand with a criminal. "Plan" of course being the word, so yes, Krav Magra if this is within your capability.