Don’t just put things down; put them away. I have to remind myself each time, but it really helps to keep clutter off the table or desk.

Another: when I sit down at my desk, I do a quick scan of everything and assess what I won’t need, or haven’t needed the past few days, and remove it. (Anything decorative is obviously exempt.) Again, I’m not perfect about it – there’s an old scribble pad with no blank pages that for some reason I can’t bring myself to throw out even though I haven’t opened it in over half a year.