Work in a relaxed, natural, upright position and let the chair support you. Your elbows should be near your body and level with or slightly lower than the keyboard so your hands rest lightly on the keys. To help you keep your wrists straight, the slope of the keyboard should be no more than 25 degrees. Try not to hit the keys too hard; using too much force creates tension in your hands. Also leave enough room on your work surface so you can freely move the mouse (or other pointing device), and be sure to rest your hands occasionally.
Varying Your Posture and Movements
While sitting at the computer, try to vary your posture and movements. Your seat and backrest should be wide enough and there should be enough room under your desk so that you can sit in a variety of positions throughout the day.
Be sure to occasionally stop working at your computer and perform other tasks. Also take periodic breaks; stand up, stretch, and move around.
Lighting the Room
While it is important to have adequate lighting in your work area, make sure it is not too bright. When a light source is very bright, your eyes get tired by having to continually readjust between the relative dimness of the screen and the bright surroundings. It is best to control the amount of daylight that enters the room and keep bright light sources out of your field of vision when you are looking at the screen.
Using Your Computer