Like everyone else said, practice, practice, practice. But I also have a little anecdote that may or may not help you. I'll share it, if you don't mind.

Many many moons ago, when I was in middle and high schools, I was terrified of getting up in front of the class to speak. I mean, absolutely petrified. In fact, I was so terrified of the prospect that I would take zeroes on entire assignments because I would have had to present them to the class. It's the main reason why I didn't get a 4.0 in high school and instead got a 3.0: entirely, 100% stage fright.

Then I went to college. Part of the core classes was a Speech class. It was required. We had to do it. I decided that I'd take it as a summer class, so I could get it over with in 3 weeks instead of stretching it out across an entire semester.

I got to the class, sat way in the back, and shook and sweated and just generally felt awful. The teacher gave us the first assignment. "Bring a book and read a passage out loud to the class."

OK. I can do that! I brought The Hobbit, one of my favorite books of all time, and I read the first chapter out loud. I could focus on the pages and not the people, and I just pretended I was reading out loud in my room. It went... okay. I was still nervous as shit, but I wound up doing it and I got an A, mostly because, I mean, how hard is it to read out loud?

The second assignment was to describe a quality in ourselves to the class. Serendipity struck, and I decided to tell the class about how terrified I was of speaking in front of people.

"Um, um... -cough- uh, hi. Um, my name is, uh, Jemaclus, and I uh... I mean, my quality is that I'm, uh, totally terrified of, um, speaking in front of people, because, um, everyone is staring at me likeyouareallstaringatmenow um, and uh.. it makes me, uh... nervous, and I say uh and um a lot, and I shake, and i, um..."

I basically spent my 5 minutes in front of the class describing anything and everything I was doing and feeling and I even acknowledged that we weren't supposed to be doing any of these things because the teacher had explicitly said "don't say um" before! But I was legitimately having some sort of anxiety attack or something. I just kept talking, and eventually, the timer went off and I shakily made my way back to my desk and hyperventilated until I calmed down.

At the end of the class, the teacher handed out her scores, and to my very, very great surprise, I got an A+. On the side, she had written a note: "Great acting!"

Whiskey. Tango. Foxtrot.

I hadn't been acting! I was legitimately about to shit myself!

And that's when I had an epiphany, which is sort of the lesson of this anecdote. The epiphany was this: people project their desires onto you. My teacher wanted to believe that nobody could possibly be that bad, so she chose to believe that I was acting. She didn't want me to fail. Nobody in the class wants anyone to get up and make a fool of themselves. They want to see someone do something successfully. In most scenarios, they don't expect perfect oration or flawless performance, just enough to enjoy it! (Alternately, she just felt bad for me... but I like my version better.)

A second mini-epiphany came after class. I was talking about it with my classmates, and they all admitted they had been so terrified of their own upcoming performances that they barely noticed mine. Instead of listening to me, they were mentally rehearsing their own speeches. In other words: not only did nobody want me to fail, most people weren't even paying attention!

For the next speech, we had to teach the class how to do something. I decided to demonstrate how to juggle. It was physical, so it was something that would keep my mind off the people watching me. It worked... And not only did it work, but it let me sort of realize that literally nobody was paying much attention except for the teacher, and _she_ wanted me to do a good job. And I got another A.

I got straight As in speech class. It was the most terrifying three weeks of my life, but I made it. And I realized... it wasn't that bad. Not only was it not that bad, but I went on to change my major from computer science to theater. In the last 15 years, I've performed in over 40 stage shows in front of thousands of people. I eventually became a high school English teacher, and I stood in front of 150 teenagers a day for nearly two years before I switched back to computer stuff. (I'm now a Director of Engineering at a startup.)

With theatre, with teaching, I put my lessons to use: nobody wanted me to screw up. People who pay $30 to see a play don't want to see a terrible actor -- they're more likely to interpret any screwups I may have made as intentional and think "Huh, that's weird" and not "HAHAHAH THAT DUDE TOTALLY FUCKED UP". My students were a bit harsher, but at the end of the day, they saw me as an authority figure, and thus on some level, they wanted me to be competent. Any mistakes I made were chalked up to... I don't really know. But I've had former students come up to me years later and say they loved my classes.

This is a bit rambling, but here's the point of my story:

We (the interviewers) want you to succeed. We want you to do a good job. If you make a mistake, it's okay. Generally speaking, we're not trying to find any tiny flaw -- quite the opposite, we're trying to find promise that you can and will become better.

We're rooting for you. We really are. We want you to be awesome. If you're awesome, then we can hire you, and we don't have to sift through any more resumes. If you're awesome, then we don't have to talk to anyone else. If you're awesome, then our work load gets lighter. If you're awesome, then a lot less stress sits on our shoulders. If you're awesome, then we look good to our peers and our bosses and our employees. If you're awesome, then everyone wins.

I'm not looking for perfection, either. But I need you to demonstrate to me that you have promise. There are tons of things I can totally teach you. Don't know what a REST API is? It would take me 15 minutes to explain it to you. Don't know what an MVC pattern is? You can learn it.

It's nice if you already know those things, of course. But what I'm generally looking for are smart people with lots of promise, even if they have some anxiety.

Most of all, I really, really, really, really, really want you to be awesome.

Try framing it in your mind like that. It might not work for you, but it worked for me.

It's not really enough to just "not suck", but that's why you should keep practicing. Practice makes perfect. It's harder to blank out when you've practiced so many times that you couldn't forget it if you tried.

Good luck. I'm rooting for you. And if you're in the SF Bay Area, shoot me a DM. I'd be more than happy to practice with you.