Starting up a conversation can be tough.
I usually choose something from my surroundings to comment on: food, drink, decor, people, music, art... "Isn't this Hallmark card display well lit?" (I only use that when I'm shopping at Target and standing next to an appealing man or woman in the isle.)
Sometimes just saying "Hi" and looking the other person in the eye with a smile on your face can get them to open up.
Mrs. LM