Step 1: Your longe line is a mess. No matter how careful I am while longeing, by the time my horse is back in his stall, this is always what my longe line looks like.
Step 2: Smooth the whole thing out, and fold it so the loop is down and at the bottom of a large coil; this is about two feet long, total.
Step 3: Coil the whole thing up, being careful to keep it flat and smooth. I do this step over my arm, and just laid it down on the tack room floor for photographic purposes. Leave the snap as a tail, about half as long as the coil itself. Once you get to know your longe line and have done this a million times you'll get a sense of how long to make the coil to get the optimal tail length - but there's really no wrong length as long as it's shorter than the coil.
Step 4: Double the tail OVER the coil, a few inches from the top.
Step 5: Wrap the remaining tail around the top of the coil - snug but not tight, so that the coil stays together but not so tight that it's distorting.
Step 6: When you've got a tail that's a bit longer than the remaining height of the top of your coil, come around from the back and up and through the top. If I'd just gone through from the back, it wouldn't be as secure: you want that last wrap around the side of the top before you go through.
Step 7: Pull tight! You've basically made a knot, and the bulk of the longe line means that it's tough to make it too tight. (Not impossible, though, especially with those nylon longe lines! So be careful.)
Step 8: Hang your longe line neatly from the snap. Gravity means the knot will stay. You can also slide a hook through the knot itself if the hook is too thick for the snap; it's not quite as secure, but it works.
Does anyone else hang their longe lines this way? any other techniques that leave a neat and secure longe line?