People are spending more and more time in front of computers and on desks absorbed into the files and worksheets and end up with craned necks. So, what is the remedy? While you are sitting in front of the computer, it is always useful to learn typing because it helps the person to focus on the screen instead of keyboard. This way you don't have to spend whole time straining yourself looking at the keys. This way your neck is not bending over. While working on the files and worksheets, use a slanting board (like the drawing boards or the boards seen at the architects offices) or some accessory which you can use to place the files to look at them easily instead of bending over them. Always work in good lighting areas and make maximum use of the day light. It is good for the body too. And, take frequent breaks while working so that your body is not cramped into one position for a longer period of time.
Also, it is very important that you do not bend over anythign unless you are bending to pick up something. Do not ever sit hunched up or slump while sitting. It makes you look fat, unconfident and really unattractive. Sitting in the upright position indicates you are attentive.