Step 1: Stack the Leaves
First take a bunch of leaves and stack them all them all together. They don't all have to facing the same way, they just all have to be flat.
Step 2: Roll the Leaves
Step 3: Cut the Roll
If you are familiar with fine chopping then do whatever you normally do to protect your fingers while you cut.
If you are new to making cuts with a sharp close to your fingers then it can be a good idea to fold your fingertips under the hand that is holding the food in place. You can use your upper knuckles to guide the side of the knife as it moves up and down to make the cut. This isn't the most comfortable way to cut, but it will definitely protect your fingers since they will be safely kept out of the knife's way.
Step 4: Separate the Strips
That's it - you've just cut a Chiffonade.