I’m also quite new to Rotax karts, and still learning, but here’s what I’ve learned over the past 6 months:
Set-up: This might seem obvious, but maybe put some more camber in the fronts to help grip coming out of corners so you can get on the power earlier. Also widening the rear width a bit will help. People might reference the power valve, but I haven’t found too much benefit by messing with it.
Driving: I’ve had to force myself to get out of the late-apexing tendency I’ve gotten from rental/indoor karts and hit the geometric apex. Also, with the Rotax, start getting on the throttle very early in the corner just enough so that the power valve doesn’t bog you down when you really get on it coming out of a corner.