This is something that is very easy to mess up. There are a lot of ways to do it wrong, but one way to do it right. :)

I've been making a lot of jewelry recently and I'd been finding myself spending a lot of time trying to get my jump rings back into shape after opening them the wrong way. Lately I find myself screaming "CURSE YOU, JUMP RING!" significantly less.

Video is on the last step!

Step 1: What You'll Need:

two tiny sets of pliers
jump rings
things to attach jump rings to, like a chain or clasp

Step 2: Opening, Part One.

Grip your jump ring on either side of the split with your pliers.

Try to get as close to the split as possible, but make sure your pliers are not touching!

Step 3: Opening, Part Two.

Twist so that one hand comes toward you and the other goes away from you.

Open it only as far as you need to - base this on the size of the chain/clasp/object you're connecting it to - if you twist too far it can get a little distorted.

While it's open, connect it to whatever you're using.

Step 4: Closing.

Grip both sides of the opening as before and twist it shut.

Make sure not to pull outwards or the ends will not meet up!

Step 5: Other Info + Video!

The photo on this step shows three jump rings opened with multiple methods.

The one on the left is the method described here - you can see that it looks quite clean. The other two were opened by pulling the ends outward and by placing a closed jump ring on the end of a pair of pliers and opening the pliers slowly. You can see that these really distort the ring.