Document your configuration!
Oh dear! Yesterday I tweaked some things regarding my mail server and to be honest: I got lost in the configuration. Although I still had the tutorial at hand which I followed I had to search for a lot of stuff. A task for today is now to go through every bit of my server and document every tiny bit of it (including tutorials used for setting things up) in my personal trac :)
I hope everyone of you had a nice New Years eve and I wish you the very best for this new year 2012!