How do you start a conversation with a stranger

Truthfully i really was wondering how to start one. There are times where i want to enter a convo yet cant because i am a stranger or i met someone interesting and want to give a complement yet at the same time cannot give a correct or good compliment. Though there are other times i have struck a convo and have made friends. So a question how do you start a conversation with a stranger? And do you have any interesting stories you have had with people you have just met for the first time?