Ginkgo, Part Used and How

Which is the part of the ginko tree that's usually cultivated and sold? How would I prepare the leaves or nuts as a herbal preparation?

The leaves, just before they turn yellow in the fall are used. Strip them off the tree (don't strip the whole tree) dry in a shady airy place and store in a dark jar. Use 2-3 to infuse with hot water for a tea.
The nuts are borne on female trees only, but until mature you can't tell which tree is what gender. These nuts are enclosed in a very foul-smelling fruit. Harvest when they fall off the tree and collect using rubber gloves. Strip off flesh( Using rubber gloves) Crack and enjoy cooked in soups etc.