How can I prevent cramping/soreness in arms/wrists?

Cramping. Eating potassium rich foods, increasing your intake of vitamin c, drinking plenty of fluids, gentle stretching, massaging, heating pad, hot shower or bath, and or ice to the affected area are common treatment options for cramps. Relax a cramped muscle by taking it thru range of motion. Consult your doctor if cramps persist as they may be secondary to a medical or neurological condition.
Arm cramping. One can reduce arm/wrist cramping by ensuring that one's ergonomic situation at work and at home is maximized. The height of the chair and desk along with mouse and keypad are variables that if used incorrectly can hasten these overuse complaints.