Balance on the ski and a stable position are critical to slalom success. And most importantly using even weight distribution with your front and rear boots will keep the ski down and working it's best.
Easier said than done, the last thing you want to do is head over the tip of the ski.
So let's break things down. In the pull it's a matter of pushing on that front foot, trying to keep the gap to the handle. This move will automatically create pressure on the front of the ski without getting dangerous.
In fact the posture coming from the offside pull is the hardest thing to master and defines how deep down the line you can run.
For the turn, you'll see pros standing tall on the front of the ski and engaging the tip for a solid turn. To stand like that requires you have had a great pull and are now free from the boat to cast out on edge.
By engaging the front edge of the tunnel the ski will slide and turn, and leave you balanced at the finish, ready to stomp your front boot into the next pull !