This is not, not, not an exact science, so don't worry if your leaves end up looking a little lopsided. They'll be layered anyway, so no one will ever see an entire leaf at once.

After you have the outline drawn, you can add additional detail (some of my leaves were more detailed than others, and it causes the light to reflect differently, which adds some depth to the wreath), and then cut out the shape. I used a regular pair of craft scissors, and they worked really well.