RSI is typically the result of a mismatch between what your body evolved to do, and what you are actually doing. In their natural state, humans collect fruits and vegetables, hunt game, carry their young, and explore their surroundings. To succeed in the modern world, humans sit still, focus on a tiny area for long periods of time, slam their fingers repeatedly against artificial surfaces, and ignore their surroundings. Unfortunately, building up the resources and free time to explore our surroundings often means hammering out that last bit of code, or finishing up a document with just another thousand mouse clicks.
This project documents what I have done to control my RSI. Controlling yours will be different and you will need to research, experiment, and listen to your body.
Resources I found useful: "Repetitive Strain Injury : A Computer User's Guide" by Emil Pascarelli and Deborah Quilter. Both authors have new books that are probably also good. Hand University
has great pictures of the wrist to help you understand what might be inflamed. The ATIC Lab at MIT
has resources and also allows students to borrow various keyboards and pointing devices to try them out, which is truly invaluable.
For me, the hardest part of this process was listening to my body. The pain usually does not come immediately, so it is often very difficult to determine what activity caused it. What I found is that pain is not discrete. There are levels of feeling before true pain that can signal distress or damage. Generally, these manifest themselves as "being aware" of some part of your body. For example, after typing on a small or badly positioned keyboard I will become aware of my wrists; I try to recognize these signals and take a break or stop to prevent progressing into pain.