The keyboard position should allow the wrists to remain as straight as possible. Research has clearly shown that pressure in the carpal tunnel increases when the wrists are bent during repetitive motions. New designs are attempting to avoid this position. Yet ergonomics is not the whole solution. Prevention requires adjusting individual work habits.
Stress is an enemy.
It depletes oxygen and blood to the body, tenses the muscles, and compromises the immune system. Managing stress means taking breaks - big ones and little ones. The going advice is to be away from the computer for at least fifteen minutes every two hours. These are small moments to simply close the eyes, take a deep breath, rest the hands and arms, get up and stretch, and so on. These micro-breaks not only prevent injury, research clearly shows that they actually increase productivity.