My tip: don't start.
Random people coming up to me, usually stating something perfectly obvious that doesn't need stating ("Cool Hat!/Hey it's Hot Today/How about the footy eh?"), and then trying to converse on a variety of boring subjects (the weather/politics/footy/where I bought my hat/vaccines are evil/Jesus Christ is Our Savior) is a colossal waste of my CPU time.
Don't be that annoying person. Live and let live.