something I try to think about is keeping my hips countered on my edge change then all you have to do is reach forward at the buoy.
An example, LFF going into 1,3,5 your hips should already be facing the shore line behind the boat and shoulders open to the boat, the key is when you start to unload and edge change your hips need to continue to be facing outbound and then start rotating your uppderbody and like Horton said start to rotate your left shoulder forward. That is the easy side.
Where I struggle (Being LFF) is going into my 2,4 turns. Your hips are more open to the boat naturally due to your stance and it is more difficult to keep the hips pointing outbound on your edge change. What helps me on that side is focusing on keepimg my left shoulder back and keeping the handle in tight on my hipso I can keep the ski moving outbound. As soon as your left shoulder starts to move forward your direction shifts down course