Addendum: At Maxcactus's suggestion I include some of my techniques for approaching strangers.
- I approach with a playful, friendly smile---usually with a "Hi".
- Ask an easy question--or make a comment--usually related to the situation: e.g. "That's a classic old rig you got there--How long have you had it?"
- Pay careful attention to their response--looking them in the eye.
- Build my next response on what they just said. Often it will suggest a follow up question and voila--the conversation is rolling--Let it flow toward their passions--that's where the gold is!
- Get the "feel" of the person and respond appropriately--
- I Keep in mind what I'm really after: an authentic unfolding of their personality and values and notable experiences. Specialized data is occasionally useful. All of these will very often flow out of them naturally and easily in the presence of someone genuinely interested in them.
- Have a feel for when to gently close the interaction.