Dress right, I think I already hit this subject, but proper dress can save you a lot of trouble. Too much and you will be overheating, too little(far worse of a situation) and you will be struggling for warmth. Every ride has a different suitable atire. from the cold brisk road ride that you know the first hill will warm you, to the epic adventure when weather is unpredictable. Know the weather and know where you are going.
I had a chill this morning on the half commute. A wind vest would have been useful. Pro cyclist were known to stuff a piece of newspaper down their shirts when summiting a mountain top. Wind cuts and can be welcomed, but often wished away. So be smart and I guess for point of this post is to be overprepared rather than under.