I've got to agree with pretty much everything scirel said. Viajero Joven taught me a while back that the most important thing you can have is re-route options. While you have to read each gate agent individually, it's important to be flexible & be willing to take other options. Now, when I travel, I always carry along reroute options (from each airport I connect through to my final destination) - I print out options for the airline I'm traveling on, their codeshare/alliance partners, and then a non-alliance/codeshare partner (also good to have in case you ever need to invoke Rule 240 - which I actually have a printout of NW's rule 240 in my carry-on).

Remember, if you don't like the compensation, you don't have to give up your seat. I always try to check the numbers before I leave on a flight - that way I can be more knowledgeable - if it's a possible oversell situation, I just say a version of PremEx's speech - "I understand your flight's oversold, if you need any volunteers, please keep me in mind - I'll be right over there" and it works.

I've gotten free CO Currency from the GA's in FLL twice for volunteering my seat when they didn't end up needing it just out of appreciation.