"testing for human kindness" with a big ass smiley face. This sign has always worked for me.
WOWEh, I'd have to be pretty desperate for a ride and/or interested in receiving something else if I wore a short skirt on the side of some road in Bumblefuck US of A. As a tactic for getting picked up, I'm sure it works. As a tactic for not becoming later raped, well, it all depends really.
I always write home really big so that people will assume im not homeless. And I also write the direction and the city because sometimes people who are on the road for the long haul, especially now with GPS and people might not have looked at an actual map, they might not realize what they are passing.