To preface this post I am not a god at online hookups. In fact I have maybe a 20% match to phone number rate, and even less actually meet in person. Over time I have tried a few things, but this by far has been the most successful conversation starter.

Call her "trouble."

It's really simple, find something in her bio or in her pics to point out and say that must mean she is trouble (favorite place, music, tattoo, sports team, activities). A strong majority of girls have returned with a message ranging from, "Of course I am" to "No, just trying not to fall too fast for the wrong guy." Some are playful about it and others are mildly offended. Regardless, any response is ten times better than nothing.

I have also used this outside of Tinder with better results. There is no substitute for the right facial expressions.