I have Raynaud's and find this guide informative:
http://www.medic8.com/healthguide/articles/ray nauds.html
I am affected in both hands and my left foot. I wear oven gloves to handle frozen foods because that will trigger an attack. I have an insulated glass for cold drinks and avoid air conditioning and cold draughts from fans - especially in the car when I'm driving.
I also have a pair of heated gloves that plug into the USB to keep my hands warm whilst at the pc. :)
In the winter I have pocket hand warmers when I'm out and about.
I find wearing a woolie hat also helpful as this keeps my overall body temperature up.
I avoid extreme temperatures - I wear rubber gloves when washing up, for example.
A spasm can be very painful, especially when my hands are warming back up. The whole thing can last from a few minutes to many hours, making handling things and doing practical tasks impossible at times.
There is not always a trigger - it can come on suddenly even when I'm hot. It can be a reaction to stress and tiredness.
If you smoke it is imperative that you stop. Gangrene will be a bigger possibility if you continue.
I can go weeks without a spasm - it is not all doom and gloom.