It can be very difficult as a beginner to throw in quick, efficient turns on a narrow track.
Staying on a single edge can also be tricky as the natural camber in the board will bring you towards one side or other of the cat track.
Just trying to stay flat is also very problematic as described above and riding on a very low edge angle can be very difficult to master as a beginner.
To keep the board going straight and true while also avoiding the dreaded edge catch, I find it's good to pick an edge and focus on digging that edge in with your back foot while keeping the board flat with your front foot. This will ensure you avoid drifting towards the side and also prevents you catching an unwanted edge. I also find this easier on your leg muscles so there is much less burn, you can just relax and let the board ride.