1) Leave a trip plan with someone you trust
2) Give specific deadlines. "If I'm not by Monday night. . ."
3) Give specifics of who to notify, and where to search
4) Give the location of your vehicle
5) Give a location of where you will head in case of trouble
6) If you carry nothing else, carry a whistle
People that don't do this are rude, IMO.
If you've ever been involved in a search and rescue, you know that the people doing the searching want information. When the only information given is "He said he was going north for a few days" or some other vague horseschit, people immediately begin to not care if you're dead.
Travis