For the most part, I won't start conversations with strangers when I don't have something specific to say or ask.
Just today I was at a drugstore and walked out to see the new Porsche SUV parked beside me. The owner was still sitting inside so I started a convo with him asking about his ride.
Now on the flipside, there is a girl at my gym who I see there every Sunday. I want to walk up and introduce myself and hopefully get to know her better but I don't want to seem like those guys who go to the gym just to pick up people so I just glance in her direction every once in awhile to see that she is also looking at me
.......ah well, next week I'll introduce myself and either get rejected, laughed at or kicked out for fratinizing