I dont no about anyone else but,
when i do hooks i dont go at it as fast as i can, you obviously need a little speed ( cant just go at it at the speed of a turtle with a limp)
I find if you go too fast you can not lift your bike has high, making it alot harder
I also think you can consontrate on the technique more when going at it slower.
You need to try and convert your weight from where it is when you lift the bike up to the front as soon as possible, when i do hooks i think im starting to lean forwars pretty much just as my back wheel is about to leave the ground,
As soon as your back wheel then touches the wall/rock push forward on your handle bars and move your bum towards your back tyre, this makes a sort of flicking motion and gives you grip on the back.