I get asked this so many times....
anyone got something else to add?
Kite are made out of nylon,plastic.....petrolium based materials. The main enemies are UV, abrasive materiaals.. sand and movement in the fabric. Most depower cords are made of braided line that therefore runs through a hole in the bar which is under enormous tension. Many were Darren Marshall's tips and tricks as he taught outside the IKO course..
1) As soon as you have finsished with a kite, pack it up, the UV, but sepecially the flapping will destroy the trailing edge.
2) When rolling up to finish, grap both end of the wingtips, especially with one pump systems and then roll then up. you roll once, and the sand is rolled up on the outside of the canopy, and not the inside..
3) A wet salty kite is OK, a slightly moist kite rinsed out in freshwater will grow mushrooms.
4) set up and check you kite for pinprick holes, a simple small patch will fix it, otherwise one large smash and it can end in tears.
My tips
1) When landing wind you lines up a bit,never leave a bar and lines that has a weaved depower cord wet in the sand, the sand works it's way into the inside of the cord.
2) spray your pump with silicone spray every 3 months in the season, your pump will last for 4 years.
3) Dont leave your kites in extremes of heat: most valves are vulcanized onto bladders and will die.
4) if your kite is losing pressure get to the shore, dont try and land, pull the safety system.
5) know your "deathleash" works, and after big crashes, check it.
Great tips, cheers.
The one thing I would add, and it was mentioned a couple of months ago, is to check for and remove any sand from between the leading edge and the canopy. The sand gets caught in there and wears away at the canopy with every little movement of the kite. Then, when you crash the kite leading edge down, its the front few inches of the canopy that take the most load, and will also be the most worn from any trapped sand, leading to the starting point for a rip.
Keeping the sand to just the outside definitely helps. There's nowhere for it to get caught.
-check over your gear regularly, lines, stitching, pulleys, bridles, etc. Picking up faults and defects with your gear can save the kite or you in the future from a failure.
Great topic Dave,
Here's another handy hint. Remove the inflate plug from your kite at the same time as you pull the deflate plug. This stops the inflate valve from stretching and getting loose. By removing the plug, it allows the valve stem to return to it's original diameter ensuring you have a tight fit which wont leak.
I'll add more as I have time. 
DM
- Wash your bar and lines with fresh water after each session, your lines will look and feel new after 3 years
- Use random packing methods as bending your kite from the same part over and over again will kill it
All good advice but if your gear still looks new after 1 year you need to kite more often.
Bar and lines that last 3 years, I have to get me some of that fresh water. I would love to get more than a season out of my lines.
-Lines wear quicker in the section they cross when doing loops and rolls, when you notice they have worn you can flip your lines to increase there life span, as long as they have the same connection each end.
Couple more...
1)put the hose nozzle in the valve just enough to seal it. Ramming it in will stretch the diameter of the valve and slow leaks will be avoided.
2)On all multipump kites, take out the deflator sticks once the struts are deflated. Leaving them causes the one way valve not to seal properly.
3) get all knots out of your lines. This weakens the line by about 30-50%. Chew on the know a bit, it will work loose, no matter how tight you think it is.
^^^ all great points 
Also spray your lines with silicone spray, particularly in the couple of meters where the lines cross when twisted (e.g. after a backloop)
See - they're not always useless twats. Just mostly 
