Take breaks, and..
If keyboard is lower than desk surface, tilt the back edge of the keyboard slightly down.
Keep wrists in a neutral (straight) position—not bent up or down. Keep elbows at a slightly open angle-90? or greater. Keep shoulders relaxed, and elbows at side. Don't use wrist rests or armrests while typing-only while resting. If you have a broad chest, consider a "split" keyboard.