make polarising statements,

if you want to break it down 'X is the worst/best part bout Y' make sure its a popular opinion if what your talking about can easily offend,

e.g. saying to a one direction fan 'The worst part of one direction is the fan base' would obviously get a negative response where as saying the fan base is the best part would lead to further discussion which could be averted from the subject at hand

once you have a persons initial interest by something like that you can move onto the boring questions like 'so where are you from?' etc

I had typed all this out for a comment on another sub but realised that wasn't what op was asking for but i thought you guys would appreciate