Not too many rules in concession speeches, but there’s one biggie—credit your opponent for … something, and wish him/her luck.
Listen to Christine O’Donnell as she A. Doesn’t even mention Chris Coons by name; B. Doesn’t wish him well; C. Gives him, uh, advice.
I will not miss this woman—though she was awfully entertaining.
PS: Here’s Coon’s speech. Go to 8 minutes and he praises Mike Castle, a Republican. Go to 15 and he praises O’Donnell. Classy.