In fact, in more cases than not a smile works as well as anything. If you can do it without disturbing or altering the routine, the results can be rewarding. This can be especially true with children and their parents. You might be zeroing in on an ideal shot of children playing and being silly, just being children uninhibited by adult rules, when a nearby parent pops in proud as a peacock and insists that the child pose for your camera, ruining the candid naturalness of your intended image. If you take the time to get permission to photograph children, it is quite rarely denied.
Grandparents are a virtual push-over.
Just try to keep them from disturbing your stealth as you zero in. While you might feel awkward shooting people from another culture or racial group, in most cases people are much more alike by nature than you ever imagined. A smile is a smile is a smile and small courtesies are appreciated all over the world. Asians are no exception. You will always encounter the cranky and unwilling but with care and sensitivity you will succeed far more than you fail.