your old, long fluorescent light bulbs: remove and dispose of them the right way. I'm passing along this information in case you, like me, do not have experience with this. Thanks to the internet I was able to quickly find the exact information I was looking for! :)
And if you ever accidentally break one like I just did, you will need to know how to safely clean up the mess. On this page I found two sections that were helpful -- "Before Clean-Up: Vent the Room" and "Clean-Up Steps for Hard Surfaces."