Since I don't make friends easily, maybe it's just me, but I can't help but feel that approaching a stranger would not necessarily have the desired effect, if you are trying to start friendships. Having a total stranger or near stranger come up to me to say, "Hey, how are you?" and attempting to start up a conversation as though they know me would just make me wary and confused. I'd probably think that I should know them and have to fake my way out of it...
My husband on the other hand, talks to anyone, anytime and he seems to be a person magnet, too, with perfect strangers telling him their life stories. It's downright weird, really.
Some of the scenarios may be appreciated, like someone looking at maps but I would wait for them to ask for help.
I think joining groups of interest to meet like minded people would be the way to meet new people and develop friendships.
I hope you find a way of becoming involved with people in a way that is rewarding to both you and them.