I've always got a couple of feet of para cord on a key chain or wrapped up as a knife fob, this is great for practicing your knots.
One way to keep a nice length of para cord available, take a medium sized key ring,(the coil kind) stick a small piece if the cord under the leaf on the ring, keep feeding the cord thru the center, and winding the cord around the ring, eventually the ring begins to look like a ball. Finally after the cord gets too tough to push through the center tie a loop on the end and put it on you keys.
I'd bet you could get 6' to 10' on a ring, now that's alot of para cord.
It also makes a nice knife fob for pulling your blade from your pocket.