I use the following routine, which may give clues perhaps:
http://www.youtube.com/watch?v=TfGT2qbvBpA
skip the balbbers if you want and move to min 2.30, with my accent I would be barely understood anyway.

If you never did those exercises before, begin gently for at least 2 months. It is basically an intensive version of wrists exercises well known.
In over one year I never had a problem - of course i may still have, but if the routine were dangerous in itself, problems would have arrived in a few weeks.

You can also adopt a gentler version of the same exercises. I would actually recommend a much gentler one it if you never did wrist training before.