If You Think Your Site Is Affected By Panda, What Should You Do?

In this video concerning the effects of the Panda update, Google's head of search spam, Matt Cutts, answers the question: "Recently Google has integrated the Panda update in to its normal indexing process. Now, how will webmaster come to know whether her site is hit by Panda? And, if her site is already hit, how she will know [...]