Try taking the same edge you do on your three but really try to take it straight up and wake to wake. Pop straight up and wait real long to initiate the spin. For instance, when you think you should start spinning, wait another second or two. This will help you pop straight up and ensure you get a nice solid handle pull. Thats the key, to pull the handle really, really hard, with both hands to your rear hip. The harder you pull the handle, the faster you will spin and the longer your rotation will last. As you come around to 360, with the handle in your forward hand (left if regular, right if goofy) really focus on keeping your eyes looking toward the opposite shoreline. Then make the last handle pass in front of your body. For this one, I usually think about clapping my hands in front of me, I dont know, it just seems to help
finish the spin by putting the handle on your hip or in your back pocket (exagerating this usually helps) keeping your eyes up on the shore and edging away from the boat. Good luck, if you have a tramp, practice spinning 5's and 7's but make sure you are bouncing straight up and trying to spin really late using only the handle to initate your rotation.