There's one single rule you should follow to reduce your chances of being killed on a bicycle. Never, ever, get trapped on the inside of a bus or lorry in the left hand lane (in the UK). If you're tempted to go up the inside, don't. If you do anyway, make sure there's a pavement you can jump onto if the traffic starts moving.
Very sadly, a cyclist was killed yesterday by an olympic bus, because he didn't follow that rule. Bradley Wiggins may or may not have recommended wearing a helmet, but that would have been irrelevant in this accident.