Head towards the jump at your normal, comfortable jumping speed. As always, you will get more and more comfortable with jumping and be able to go higher when doing this trick. You should know before you jump which hand feels comfortable to come off the grip, in the end it helps to be comfortable doing one-handers with either hand. Right before reaching your maximum height release the grip with your hand. At first do not remove your hand from the grip, just open your hand up so you aren't holding onto the grip tightly. When landing close your hand back around the grip and land normally. Obviously you want to do more than open your hand up in the air, but one-handers allow you to progress to really streching your arm out. After a few (dozen) tries with opening your hand up, begin to pull your hand slighly away from the bar. An inch or two at first, but within a few hours you should be fairly comfortable taking your hand a foot or more away from the bars if you are jumping comfortably.

My favorite variation of this trick is the One-hander lander. This is rather easy once you are comfortable with just doing a One-hander. Simply, don't return your hand to the bars. It is more of a challenge mentally than physically. On impact, hold the bars just enough to keep them straight, but not too much. Use the non-bar hand to help keep your balance. It is as easy as it sounds.