Simple and quick Method
This is very easy to apply,
use a glue that is thin enough to apply with a brush and is slightly tacky after a few moments of being applied.
Lay the leaf over it - cut to the size of the area you are currently working in
Use a soft artist's brush to press leaf onto the worked or glued area
then brush away the excess, keeping the bigger pieces for other projects.
I usually spray with clear lacquer to protect the surfaces and the gold.
Allow to dry completely 8-24 hours.