This is a difficult one, because telling a teenage girl not to do something is a surefire way to get her to do it. I would recommend you encourage her to travel, although I would act slightly disappointed in her choice of destinations. Continental Europe is so typical, kind of on the beaten path. Almost cliche, That is where everyone else goes, right? Try to talk about how if you were young, again, you would love to see the lesser known parts of America, West Virginia, Wyoming, Montana... The places you don't often see depicted in Hollywood movies. Don't try to convince her too hard, but let her know that you would judge her if she takes the conventional way out. Don't talk about niggers or muslims at all.