One kart at a time, one lap at a time. Don't worry about who is leading or who is behind you. You can't win by simply racing the guy behind you or trying to chase a leader that is 5 or 6 karts ahead. Gotta pass the one in front of you to get to the next one.
The more seat time I logged the better I was able to control anxiety. Here are some things that calm me down.
I get up to the grid early and get all buckled in. Prop the feet up and chill till its time to go.
Race to have fun not to win.
Be patient and pass clean. Don't rush it!
Have confidence in yourself and the kart.
Don't come into a race with the mind set of getting even with someone.
Don't overthink it. Once the race starts its all instincts.
I know its working when I don't have to remind myself to breath.
Me personally, I race best when I'm under pressure, like qualifying bad and having to race your way thru the field....that usually happens to me more often than qualifying good, I just hardly ever hit it right qualifying for some reason but by time feature rolls around im almost always in the race for the win or right there and I think that's what counts most....you have to be there on the last lap to be able to be in any position to win the race! I don't think alot of people think about that when on the track, for whatever reason.
I usually smoke a cigarette while waiting for the class before me to go out, it really calms me down a little and I can be relaxed when we start the race no matter where I'm starting, its more tense for me starting on the front row honestly....you never know what the people behind you are gonna do and it can be nerve racking when you're leading a race and have no Idea if the guy behind you is on your bumper waiting for a mistake or is 5 karts back not able to run you down.
Everyone is your enemy. You are all going for the same prize. Have fun, run hard, win. Being patient in a 10 to 12 lap race isn't really an option unless you start up front in which case you run like hell.
If you are tense or nervous you will probably be one of those guys that screws up someone else. Aka, that idiot. Have to be confident in the moves you are making or you can second guess yourself and cause a problem which is probably what you are nervous about in the first place.
I've found it is usually the over confident cocky ones that screw others up... I have been around some of the all time greatest drivers on dirt and asphalt.... many times being the last person they had contact with before the race started and all of them were nervous... and they were usually most concerned with the drivers that weren't... "concerned... nervous" try to find an empty urinal before the start of any big race....
I've found it much easier and get better finishes by racing the track and not worrying about the competition, capitalize on their mistakes, and race the track. when you find the fast line for your kart run it until you catch who's in front of you, then make a clean pass and go back to your line. if someone catches you and passes you go to their line immediately and see if you can stay with them and if their line is faster.