Self taught here too. Just keep doing stuff. It doesn’t have to be for a client. Find something you like the look of and figure out how to do it. Practice techniques and develop your skills. You will improve and with that comes the confidence you need. Keep learning and developing your skills. Technology changes so there is always something new to learn. That’s a good thing, BTW
StudioMonkey got into this years ago when it was possible to still get work with a good portfolio.
If you are in the USA, and if you plan to do this for a living, I’d highly suggest:
changing your career path to something other than flat graphic design
getting credentialed in some fashion. Unfortunately in the last 10 years Graphic Design has become one of those careers where 4 years of College (BA degree level) and 2 years of real world experience are considered only entry level. You can see the catch in that statement.
If you aren’t in the USA, your mileage will vary, being self-taught.
Far more goes into graphic design than making pretty pictures that “look better.” Sometimes a “pretty picture” isn’t what the client needs to sell their message. There’s a lot more theory behind it and more mechanics to the background of the file preparation.