The distance you leap at the wall at is purely what you're comfortable with...I use about a metre and a half because I'm quite short and need the distance to get a foot nice and high. As mentioned earlier, I don't twist as early as other people, so in this case, it's more-or-less like I'm just going to do a normal speed-climb (a speed climb is what we name the move where you run at a wall at pace, hit it with a leg and kick downwards in order to rise vertically and grab a ledge out of normal reach).

With my leading leg in contact with the wall, I turn my head left in the direction of the rotation. My back leg (the left) is being drawn up vertically, so that it continues my upwards momentum.

This is the 'twist'. At the epitome of the height I'll get from the foot on the wall, a quick rotation of my upper body makes my upper back face the target wall. My arms are brought around in a tight anti-clockwise arc (too wide and you throw yourself off the wall) to prepare to catch the ledge. This motion is actually what provides the majority of the twisting momentum.

This is the weirdest bit, and by far the hardest. You've got to kick downwards, not away from where you're going. If you don't kick down, you won't get the height you need (bearing in mind this wall is nearly 4 feet higher than me).
Because your lower body has a delayed reaction from the momentum provided by your arms earlier, you need to make sure that your head is rotating fast enough to bring your shoulders around (a general rule is that wherever your head is pointing, your torso will follow). Arms are high to catch the wall (and possibly protect your face if you over-rotate!).

First contact with hands on the wall. You really are rotating to fast to know where to put your hands, and you'll probably miss the wall a few times. At first, try throw your hands up slightly higher than you would imagine, and after a few goes, you'll get the feel on where the ledge is. Don't be discouraged by the lack of skin on your hands - you'll get it eventually.

Just a matter of hanging onto that wall...your momentum and force downwards is quite high by now, so a good grip is always helpful. As you can see in the picture, my body is being thrown sideways quite a bit...be prepared for this motion.

A flick with the chest, and your right leg gets between the wall and you - prime way of getting the drive to get up the wall cleanly.

When preparing to do this move, picture yourself running toward the wall. Your eyes are on where your first foot is going to be placed, and you leap at the wall, placing the foot where you aimed at. You then turn your head towards the left (or right if you're doing it the other way round) and upwards, with your arms following close behind. Whilst all this rotation is happening to your upper body, your leading leg must be driving downwards to keep you going up. The rotation is continued as your first leg comes off the wall, by which time you are nearly facing the wall. Lift your hands up high, and grab the wall. Get a good grip, let your body swing outwards with the sideways momentum you've gained. When your body swings back in, use that momentum to assist you in getting up smoothly. Good luck!