This is not a spin to win trick where you throw yourself into a spin and see where you end up. The ‘180-on, 180-off’ trick is all about showing technical control and style. With this trick, you need to be able to start your spin, stop your spin and then start it again. To achieve this you'll need to be thinking about where you're looking and the position of your body at key points down the feature.
Keeping your eyes fixed on the end of the feature provides greater rotational control and prevents over rotating. Allow your body to constantly rotate in a slow, fluid motion to avoid getting stuck in one position and then forcing the last 180. It will take practice to get a nice style but be patient and don't rush it.
Approach slightly on heel edge, open up and pop a 180.
Land on both feet equally and keep a flat base.
Keep your eyes fixed on the end of the box to stop the rotation.
With your eyes still fixed, start to rotate the upper body in preparation for next 180.
Release that tension to let your lower body follow.
Land flexed with your eyes still fixed on the end.
Utilising the end of the feature as a focal point will be key to getting solid rotational control