In the UK you are limited to 50cc when you are 16, and only allowed to progress to a 125 when you are 18 and have passed a test. even after 18 and having passed teh first test, you cannot ride anything over a 125 until you pass the full motorcycle test, which has to be taken withing two years of you passing the first test.
UK is shit hot on who can ride bikes, but we do have a low death rate.
"wear full protection" even at 30mph you hit the road in jeans and tshirt, you will get major road rash, if not ground down bones on the tarmac. imagine rubbing your elbow at 30mph along the road for 20ft.
a huge amount of accidents happen on bikes because of teh indicator designs.. you turn right for example, and forget to turn your indicator off (as they dont switch off automaticaly) the next turning you come to, that car driver waiting to pull out thinks you are signaling to turn and pulls out on you.
Buy a decent helmet, a cheap shitty one is worse than none at all.
decent tires, riding in the wet is dangerous. when you think of how much contact your bike has with teh road (2 wheels, each has about 3-4 square inches of contact). I came off doing 10-15 miles an hour in teh wet, broke my arm and fucked my bike up.
One last thing - is EVERYBODY I know that has riden or rides a bike has had an accident, just be prepared as much as possible.