my biggest problem has always been getting my eyes open!! it makes it hard to spot the landing when your eyes are shut...
In general you will spin a bit faster if you tuck up more rather than being really layed out, so maybe give that a try if you're still under rotating? But definitely, the longer you wait before changing edges the higher you'll go, and the further around you'll get.
My other tip would be to keep the handle in a bit with your leading hand - i used to have my arm all the way out, then when you land on the water the handle just gets pulled right out of your hand (like on any jump where you have the handle out). If you can get into the habit of keeping it in now, it going to make it much easier to ride away later.