Hi Kozzie,
Here is a couple of thoughts that may help you with your unhooking.
When most people try to unhook for the first time, they just disengage the donkey dick, sheet in and unhook. What most riders fail to appreciate is that when riding hooked in, we tend to ride along with the bar half way out for a comfortable amount of power. Riding like this allows you to sheet in for the lulls and sheet out for the gusts to maintain consistent power. When you suddenly unhook, the kite is powered perfectly for the lulls or lightest strength of wind you have been riding in. In the normal strength and gusts, you will find you will be way over powered and will be dragged off downwind at a rate of knots unable to perform any trick at all, usually with the kite at 12 o'clock. (No cool points here

)
Another thing you need to do is to set your safety leash to "suicide" position. "Suicide position" prevents the kite from fully flagging out when you let go of the bar. Learning unhooked whilst in full flag out safety mode can get pretty frustrating.
SAFETY MESSAGE DO NOT LEARN UNHOOKED TRICKS WITH A SUICIDE SETUP IN ONSHORE CONDITIONS OR WITH OBSTACLES IMMEDIATELY DOWNWIND OF YOU!
1.
SETUP YOUR SAFETY LEASH SYSTEM - This can differ on many bars, but basically you want the chicken loop itself to go through the flag out ring. You then clip your safety leash to the mini ring off of the flag out ring so that the flag out ring is connected to the chickenloop. If set correctly, you should be able to still release the kite to full flag out with the safety release on the Chicken loop if you pull your way in to the chickenloop. The kite will depower but not flag to safety. This can be dangerous! If unsure, have an expert look at your bar system and get help, it could save your life!
2.
SET YOUR TRIM - In order to unhook and perform unhooked tricks, you need to be in control of your power. Try riding along with the chicken loop pulled all the way in to the bar across a whole tack. Adjust the trim to enable you to do this without having to sheet out to dump power. You will probably feel under powered once you can do this as you aren't used to riding at "just enough" power. you may find that you are better served by a smaller kite than what you would normally ride. A larger kite more de-powered will make it easier than a smaller kite powered right up (less twitchy). Once you get technique sorted, you can ride more powered up. Best to learn to walk before we run though right?
3.
KEEP THE KITE LOW - The next thing to get used to is for the power or pull to come from your shoulders instead of your waist. The kite will have much more leverage on you from a higher body position when unhooked. To remedy this, you need to physically try and hold the bar down lower instead of allowing the kite to dictate the height of the bar. This will require a bit of practice and maybe some muscle conditioning. Keep the kite lower in the sky ie at 10 or 2 because you won't be able to edge hard if your kite is above 45 degrees.
4.
CONTROL THROUGH EDGING - Learn how to edge properly unhooked before you worry about trying to throw down tricks. Control over speed and direction (and the kite position) whilst unhooked is pivotal in success. Speed is controlled by edging harder and using more back foot pressure. This forces the kite further upwind to sit higher in the wind window and closer to neutral.
5.
CENTER YOUR HANDS - When doing unhooked tricks, you basically want the kite to "stay put". You want it to be stable, and remain fairly low to make landing easier. In order to do this you need to move your hands to the center of the bar next to the center line where it goes through the hole in the bar. This reduces the amount of leverage on the side of the bar when you are doing your trick. This pressure is inadvertent and usually stuffs the trick up if you are unaware of it. The kite normally goes "up" as a result of the body position in leaving the water. Keep your hands centered!
6.
SPOT YOUR TAKE-OFF - When preparing for your first trick (usually a Railey), ride along comfortably (hooked in), spot the wave or kicker or whatever where you want to launch the trick, and unhook. This should ideally be only a couple of seconds ahead of where you are at most. You don't see experienced riders doing a full tack unhooked looking for a ramp, they ride hooked until they see the ramp, then unhook and hit it.
7.
BEAR OFF TO LOAD UP - Bearing off the wind just as you unhook and easing up the edging can be good if you are after a trick that works well with speed, as it adds power and explosiveness. Bear off, drop the kite back a fraction in the wind window by doing so, then throw the trick by cranking a good upwind carve off the ramp or piece of water you've chosen. Throw the trick.
8.
PREPARE FOR LANDING - Landing an unhooked trick requires good core strength as you'll most likely be stretched out and dangling from the bar. You need to pull your lower body back into landing position beneath you. Once you land the board in the direction of travel, hook in again. If you have a hard time hooking back in, let go of the bar whilst holding the chickenloop. This de-powers the kite and allows you a few seconds to get hooked back in without the power.
This is just the basic stuff to get you started. As others have said, there are loads of other video's that focus on the particulars of specific tricks. The above info works for nearly all unhooked moves. Play around with it and explore! Lots of fun in all styles of riding.
PS, not a bad idea to warm up and stretch before throwing down a crazy unhooked power move on your first run away from the beach if you want to avoid injury. (Speaking from experience).
DM