Excercising your wrists and arms is absolutely one of the best ways to avoid RSI in my experience. I think the advantages of using ergonomic layouts are perhaps overstated in some cases, I find that if I allow my hands to 'float' a little and move around more freely my fingers find the keys easily, and I don't need to worry about planting my wrists in a fixed position and having them at an uncomfortable angle.

I imagine ergonomic designs probably makes the most sense for people that do large volumes of typing with high WPM. For me I just really like the compact layout of my FC660C, small boards allow me to have a mouse either side, swapping mouse hands is another great way to avoid RSI.