Once you've got the hang of them they feel mint! you just fly to back wheel, basically a hook is all about speed and getting used to smacking your bike in a wall at a vertical angle, feels weird because how often are you ever vertical on a bike, just takes time to get used to it, shift your weight as hard as you can to the front wheel and your back should just come straight up but if your trying for a hook to back as your rear wheel comes up stick your arse and weight to back and the same will happen to the front . I also reccomend that you start on a slant but get to a vertical wall soon after just keep trying over and over, you will get it good luck mate.