Claire, at the risk of hijacking this thread, here are a few sites that give more info
(I thought about using PM, but others may also find this useful).
National Tremor Foundation
Essential Tremor -- familydoctor.org
MedlinePlus Medical Encyclopedia: Familial tremor
Karen, you can hijack my threads anytime! Really good information. I have similar problems but my shakiness is from some nerve damage after a major accident about 17 years ago. I hope this helps you Claire.
I have a different problem. Caffeine, even the sparse traces in decaffeinated coffees and teas, gives me violent migraines. So I stick to herbal teas and love them iced in the summer. I used to love a good iced mocha but the chocolate and coffee combination is lethal!