Just keep on your line, don’t do anything sudden, and keep your eyes ahead. The faster drivers will get around you, don’t get out of the way for them. If you’re battling for position just stay predictable.
The worst is when drivers try and turn around to see who’s coming up behind them and inevitably swerve while doing so. Seasoned drivers are guilty of it too except they’re usually fiddling with brake bias or ripping off radiator tape and end up swerving all over. I was always told to stay predictable and under control. When I hear someone faster approaching I avoid locking brakes up, needing to countersteer, etc and stay exactly where I’m supposed to be.
I’ve never understood racing that frowns upon going two wide into a corner. Karting seems to take the F1 approach which is that the corner belongs to one person or another. I get it for sprint tracks but it seems to carry over to road racing too. It’s something I’d like to see relaxed for at least road racing.
My biggest etiquette issue isn’t on the track…it’s in the pits and off the track. Be nice to the people you’re racing with and help them. The dissemination of information in karting is abysmal and the people in the pits aren’t always friendly nor helpful.