Premise: 21yo male, I live in a country where it's much less normal for strangers to talk/approach outside of situations that promote it.

Problem: I have no problem approaching strangers, commenting on situations etc. on the train, grocery store, the street. Where I seem to be lacking is in escalating it to more than a couple of minutes talk, picking up whether she's interested, getting a number/Facebook. Am I wasting my effort and should be focusing on social gatherings? Same goes for those, I have a hard time timing the points of escalating, "powertalking" and generally getting past the straight "get to know each other" talk. Are there any guides I've missed, or tips you'd like to share?