It should sit directly in front of you so you don't have to twist your body every time you need to look at the computer screen. If you don't have enough room, find a better location. The top line of work on your computer screen should be at eye level. The more you have to adjust your eye and head level every time you look at your screen, the more strain you're putting on your eyes and neck. To correct the height of your monitor, adjust your chair or get a monitor stand.
Good lighting is important.
Most experts agree that overhead fluorescent lighting is not ideal. A desk lamp or other supplemental lighting source can help. If you see reflections or glare when the monitor is turned off, pull down window shades, move lights away from the reflection or tilt the monitor up or down slightly. Ideally, you should sit tilted forward slightly so your knees are lower than your hips. This is simple with most office chairs, but the chair you have at home is probably a different story.