People who help fight human trafficking: what are some tips you have for spotting illegal activity, and reporting it?

I'm not someone who works against it but I recently moved to ukraine, and in the hostel we are thought by our seniors that if someone approaches you by saying learn more about Christianity or Jesus, stay away from they they are usually women in 30s and 40s and lure the victims in the name of religion later they ask to meet up at some public spot after two three such meetings they invite the victims to shady place or something and after that there is no trace left. Even I was approached by two of these ladies in a super market and I wasn't aware of it before but I'm an atheist and don't trust people in general so nothing happened. And this is more common around international students hostels.

/r/AskReddit Thread