There is a picture about the internet I like to compare to when people complain about their ability to GM not being good enough:
I love it so much because people will ALWAYS find a reason to put themselves down when it comes to GMing or any ability, even if they’re good. There are some horrible GMs as any Internet search will be full of stories, and Knights of the Dinner Table magazine had occasionally featured stories where a character tried their hand at running a session and mostly it turned out humerously due to either player issues (the group was known to be hack n’ slash over RP) or GM ineptitude (such as not fully prepared, stealing plots direct from TV).
So, how come I joke about those examples but still try to get unprepared people in? Well, this attitude is because those comics were intended to be humorous, while in real life most people want a GM so they will work with you over rough patches. You just need to be willing to do the work.
On one place I used to play online would have 20 to 30 people on (unique players, no alts) and be asking “So, who is doing anything now” instead of offering a scene or plot or anything. That attitude can quickly make someone who runs plots bitter, because sure you get to GM but you don’t get to tell your character’s story. So, while I could rack up the experience gained being the GM and my character could advance, I didn’t feel like my character had really done anything to warrant advance and I wasn’t being challenged so I didn’t see a need to advance yet.
I learned to GM in tabletop as a school kid, probably started in junior high, mostly because no one else wanted to do it. so, I would pick up skills on the fly, since this was back before the game really got the public attention it has today. Today, there is a glut of websites and Youtube channels and GM help books that will tell you how to do things. The problem with a lot of the information is that it can contradict other information or it can be stuff that is too general like ‘Learn to Improvise’. So, you can filter information that works for you and the rest, you can ignore because the idea of the game is to have fun and if something is making you not have fun, then avoid it.
So, to takeaway from this, the only way to get better at Gamemastering is to do it. Don’t be afraid to take some time behind the gaming screen, and if you stumble and fall the first few times just get yourself back up again. There is no specific criteria to be a Gamemaster other than the desire to be one and the will to put in the work, since you’ll need to prepare things and then learn to do off the cuff when the players decide to try something different.