Have you ever heard the saying, “Every man should own at least one pink shirt”? In my experience, the key to wearing a pink shirt is confidence.
And you know what? Confidence is critical to good GMing, too.
How you approach GMing matters a lot less than maintaining momentum. If you don’t know the answer, make it up; if you’re not sure something will work, try it and then get some feedback; if you need help, ask for it; if you ran a bad session, make the next one better.
Keep moving forwards, with confidence, and many of the other myriad details involved in GMing will follow.