If visiting a cemetery where your ancestor lived, consider leaving your name and address on an index card at the stone you’ve been to visit. Put the card in a plastic baggie and use something (such as a rock, etc.) to keep it from blowing away. Don’t harm the stone in the process, but perhaps someone visiting the cemetery another day will find your baggie and contact you.

Not everyone with genealogy information goes trolling the internet, but they may go cemetery visiting.