I am not really a hitchhiker but I have been offered rides maybe a dozen times in my life.
I am a male in my late 20s. Nevertheless, yesterday I was hiking on a road and in a position where, if the roles were swapped and I were the driver, I would have probably offered me a ride.
It was evening, getting dark, it was a rural road, the traffic was not too frequent to make it dangerous to stop the car (there was maybe one car going by every couple of minutes), I was hiking southwards toward the village of Vojnic, Croatia, and there was no sidewalk. The culture of the area (north of the village of Vojnic) seems quite hospitable and friendly. Yet I walked for two hours including in the dark without being offered a lift, resting in a couple of non-operational bus stops along the way. Could one of the issues be that people in this rural area are maybe not confident enough in their English or German language ability to offer a ride? Or are people less likely to offer rides because it is on the routes used by migrants? Is there anything one can do to skew the odds in your favor a bit?
To clarify I wasn't actively soliciting rides by gesturing with the thumb up sign (I might or might not do consider doing this in the future because to my mind it has a semblance to begging), but I still thought someone might stop to help out. (I am also not normally walking in the dark - it was an exception).
Edit: this is awkward for the question, but I found a much higher level of xenophobia in southern Vojnic municipality which wasn't obvious elsewhere. I suppose this is another reason I have reservations about using the thumbs-up sign: in xenophobic area in particular, it may be less safe than other methods as it's awkward using this method to decline a lift if something doesn't seem quite right with the driver. I am therefore interested particularly in secondary methods like strapping a sign for the place you're driving to your rucksack.