Well, I'd go for obvious things if the situation provides them. Like, if you see a pregnant woman, you could ask after the baby: What will it be? Is it your first?
Or if there is a mother with a young child, remark upon the child. (Oh, how cute she is!)
The weather always does make for good smalltalk, too - especially if it's acting up the way it does here and now. (Warmest, sunniest *and* driest April ever!)
Questions you should avoid at all cost:
Never ask an obviously old or sick person, How are you today?" - This is bound to end in disaster.
If you want to inquire after products the customer bought - well, cosmetic stuff and some others are fine - but you'd do well *not* to inquire after the choice of condoms or stuff. Unless you want to entertain everybody else on cost of the unlucky customer up front. Oh, and tampons don't do well, either. *g*
Hope this helped.
Mellie