The best safety briefing that I ever listened to was given by a Caledonian girl. She used humour to get people's attention. Once the laughter started, everyone (and I mean everyone) listened attentively just to hear what was making the other passengers laugh.
I only wish I could remember the whole speech but one little nugget was "your lifejacket has thoughtfully been fitted with a light and a whistle for attracting sharks". The punters loved it.