My first race of the season is April 14 and i always struggled with race starts, when it comes to race starts i start getting anxious and stressed about it because i don’t know what will happen and how to avoid a accident like i had previously. on 14th May 2023 that was the day i won for the first time in my career after the last 4 years of struggle at 60cc (i started x30 on 2022), that day when i won, on the race start, and even before it, i felt confident like i’ve never felt before, on qualifying i got pole position for the first time also, on the 1st and 2nd heats i finished 1st, and because of a small mistake and almost “dead” tyres i finished 2nd om 3rd heat, 1st place in total, but the thing is that specially on 2nd heat i felt so confident on the start and in the race, i don’t know how but i would want to know how i can improve my race starts, if you’ve got any tips, specially for narrow tracks, because here in Panama we just race in just 1 track all year because is the only kart track here and they are planing to build another and our actual race track is pretty small and you can barely find a spot for overtaking, the last few practice days i felt very confident with the kart and i would want to improve this.
Así sea, así será, que así sea .
I found that there’s not much you can do about the worry other than accept that you may or may not have bad luck.
Be situationally aware, don’t do anything stupid trying to get up front too quick. See the bigger picture, keep your vision active, and don’t fixate on the guy in front of you.
Sounds like you have pace to qualify up front so maybe you don’t have to worry about getting stuck in the grinder.
Just race a lot. Race until it’s familiar. It never goes away fully but it does become something that you can acknowledge, and then choose to ignore. There are no shortcuts, here… only time and its many starts (and inevitable DNF’s) will allow you to let go and flow with the moment.
If it helps, remember that you don’t forget anything. When the anxiety presents itself, remember that you know exactly what you are doing and will do it well, again, like always.
Maybe what you felt is related to that. That perhaps that start where you felt good about the kart and drove it well is you beginning to trust your abilities and self.
Visor down, eyes front. 
As far as the anxiety/nervousness part, it’s scientifically proven that your body has that feeling because it’s preparing itself for something. It’s a natural part of that fight or flight instinct, and it’s statistically shown to reduce reaction times, etc. With that in mind, just embrace it knowing that it truly is a good thing. In a weird way I worry when I’m feeling too comfortable/not the usual nerves.
In terms of practical terms for the start, just recognize that being too standoffish or “friendly” will usually make it worse. I’m not saying be super aggressive or run people off the track, but you do need to claim your space and stick to it. Getting a lot of practice at starts isnt logistically easy, but I wouldn’t discount how helpful it is to do video game races online. Watching race starts on youtube from experienced drivers from different sections of the pack will help too.
I’ve got two articles for you that you should take a look at if you want to feel strong and positive at starts.
It should help you start to think differently, because if you have in mind ‘avoiding accidents’ for starts then you are already preparing to sacrifice a good start for a safe one.
This one is about starts only:
When the green flag drops the BS stops
This one is about learning to love chaos, because you are a racing driver after all:
Racing chaos - do you attack or retreat?
Embrace the start. It’s a mixture of strategy, aggression, carefulness, anticipation and luck. It’s one of the best parts of racing, especially if you get it right. I don’t think it can be taught but it’s learned through experience and embracing it. Pre-grid actions also matter, I always put on the friendly, feeble old man look, so people feel sorry for me and let me pass or won’t bump me too hard. 
I love it. 