Turn on Do Not Track.
The efficacy of Do Not Track headers is questionable, to say the least. It's a noble idea, to set your browser to automatically announce to every visited page, that its user does not want to be tracked. Whether the sites and advertisers will listen is another matter, and it could take years for the FTC or others to start punishing those who blatantly ignore Do Not Track requests. Still, it doesn't hurt to turn the feature on – check your preferences in Chrome and Firefox, click the necessary boxes, and hope for the best.