A clean desk can really help your workflow. Not only does it mean you have space, but the lack of clutter means you have less distractions, and in my case less stress from looking at all the mess. I find it very difficult to maintain a clean desk, I always leave stuff on there to fiddle with later or that I think might be useful, but never get round to using it so the mess just builds up.
A simple method I learn for helping keep your desk clean is actually pretty obvious, and only requires discipline. The rule is this: if you get something out, always put it away again when you’re done.
Basically if it doesn’t permanently belong on your desk, it shouldn’t be ther unless you’re actually using it. This means no build up, no mess and no stress.