Try keeping your head and your eyes up. At 180 try not to be looking from where you took off but at the horizon. Once past this point, then you can start to look for your landing. Oh, and forward shin pressure is a must.
I too went through this problem like almost every park skier in their beginning. What helped me was to always think about the pressure of your shins to your boots. Keeping your eyes in front of you and starting to swing the arms while going up the landing.
It helped me a lot to do it off of a cliff. getting the motion of a cork 3 like that helped me not land back seat, it really is a hard motion to learn on park jumps. Good luck mate!
