The trick is to find a flat one. Once they lay around for a while, they get dry and wrinkle up. And wrinkles require too much depth of field that a macro lens at that magnification usually does not offer that easily. Sure, bringing leaves into your studio and putting them under a glas to flatten them might work as well... but I prefer to take photos of objects in their natural environments.
And then just try different angles and compositions. Find out what works best only on a bigger screen once the image have been downloaded. You can still rotate and crop, but you loose resolution and quality in the process. So try to get as close to a good composition already while shooting.
In post processing you can then add more contrast or clarity, sharpen the image and optimize the colors. Those subjects without a background reference are quite forgiving.
Maple Leaf Abstract