Getting started and first launch by Thierry Bressure

Thierry is blunt about it: launching with the sail loaded is “the most important lesson”. He skipped this step himself, because of his indoor gliding Rev practice and a first quad-line flown with a slack sail, and says it cost him two years before he understood that loading the sail is essential to flying a Rev.

From the series KiteJust4Fun path. Transcript and translation by QuadKites.org.

Key takeaways from this video

The first exercise is to make it fly straight ahead: pull the brakes to keep it stable at a negative angle, then bring the front lines up to tilt it gradually.
Avoid launching with a big yank, flat out and with no brakes: with the lines tight on a nearly vertical kite, a little more angle is enough for it to lift off on the sail's pressure alone.
Meter the brakes to keep a straight path on the way up and down; in light wind, walk backward to give yourself wind and forward to bring the kite down.

Transcript

The kite on the ground
0:05
A first video for beginners: how to put the kite in takeoff position, then launch it to learn to balance the right and left brakes so it goes straight. The kite lies flat, leading edge away from me: to raise it, I step back and make a few shoulder movements so the wind gets under the sail, then I put it in parking position, leading edge on the ground. There's very little wind today, and my 37 m lines aren't well equalized, which doesn't make hand position easy.
Launching without a jerk
1:25
The first exercise I recommend to beginners is being able to hold the kite in one direction: making it go straight. The kite is on the ground in takeoff position: I keep the fronts far out and pull the brakes toward me so it's stable, at a negative angle. I see many beginners launch with a big yank, no brakes, full throttle: it's fun, but you don't feel what's happening. Instead, I recommend raising the fronts to tilt the kite gradually to a positive angle. Once it's almost vertical, held back by the ground, I tension all the lines: you can feel the kite wanting to take off, the sail filled, without adding anything. Just a little more angle with the fronts and it lifts off by itself, through the pressure in the sail: no need for a big yank.
Going up and down straight
4:46
I lay the lines side by side in front of me to put the kite in the most neutral position possible; the brakes are taut, and I just need to find the positive angle where I feel the wind holding the kite. I take off, and I have to make it go straight by using the brakes to correct its path. This exercise teaches you to fly the kite forward below its top speed, under pressure, and to balance the brakes to keep it on a really straight line. At the top, I add brake to bring it down, or step forward a little to cancel the wind, and all the way down it's the same exercise: balancing the brakes to stay straight.
Moving in light wind
6:59
When the wind is light, this exercise also teaches you to move: to give yourself more wind, step back; to bring the kite down, change its angle or cancel the wind, step forward. Of course, in stronger wind you don't need to move: with 10 to 15 km/h of wind, the exercise is easier to learn.