One of the security policies that has taken hold across a wide range of businesses is the "clean desk" and often the "clean desk and clear screen" policy. Intended to keep both PII (personally identifiable information) and company proprietary information away from prying and wandering eyes, policies such as these have more advantages than first glance might suggest.
First and foremost, a clean desk and clear screen policy reduces the likelihood that sensitive information of any kind will be easily viewed or even taken by someone who shouldn't have it. Even a list of employee names and phone numbers can be useful to someone crafting a social engineering attack.
For another thing, a clean desk can end up being a significant stress reducer. At least a study or two have shown a reduction in the stress level of workers when their clean desktops promote paying attention to one thing at a time. Whether or not you notice the effect, a cluttered work environment is distracting. And systems administrators are often the kind of workers who have the remnants of the last dozen or so big emergencies they've handled still scattered over their desktops.
A side benefit of a clean desk policy is that you are likely to cut down on wasted paper because most people will rely less on printouts if they have to file or shred the paper soon after they use them.
You are also likely to appear more professional or at least give a better impression if customers or big bosses walk through the room. You might think that a desk covered with papers will give you the appearance of being very busy, but it's more likely that people will simply think you're disorganized.
Admit it. Most anything you do on paper, you could do on your screen as well -- and your screen is *so* much easier to clear. ;-) And think of the increased efficiency that might come about if you spend a lot less time looking for some particular sheets of paper in that stack or two on your desktop!
In fact, you should try adopting a rule that you handle any piece of paper once and only once. Then you won't find yourself with so paper to be reviewed, filed or tossed that it could occupy you for several days.
When you leave your desk for any extended period of time (e.g., lunch), you should move papers off your desk. Particularly sensitive documents might be locked up -- especially if other people working in the same area should not be privvy to their contents. You should consider not having your screen viewable from the entry into your office or cubicle.
Printouts and various documents that you don't need any longer should generally be shredded unless you can afford to take the time to look at them long enough to be sure that the possibility of sensitive information getting into the wrong hands is not a possibility.
Making the transition from a cluttered to a clean desk can be a bug challenge for some of us, but you can move in this direction slowly if you prefer that route. Try designating a small portion of each day to cleaning up and tossing out -- and don't forget to shred anything that shouldn't be public.
In time, you can get to the point at which you always clear your desktop before going home and make good use of the lock on your drawer or filing cabinet.
Keep a clean desktop. Focus on one thing at a time. You might find that you can get more done and feel better while doing it.