My husband rides. He started riding just after we started dating, so I was able to give my opinion on the following when he decided to go for it. Luckily, he believed in all of it, anyway.
#1 Helmet, ALWAYS.
#2 Full protective gear (jacket/trousers) designed specifically for riding, along with gloves, a back protector, and boots. He has two sets - one leather, one textile - and will not even ride five minutes down the road without wearing full protective gear.
#3 Motorcycle safety course, routinely update your knowledge by taking advanced courses, etc
#4 Be aware of your surroudings. Do not push it. That is what off-road track days are for - in a more controlled environment.
#5 I also wear a helmet and full protective clothing when riding on the back.
I see people say "always wear a helmet" - well, obviously. BUT I also vote for ALWAYS wearing the full protective clothing as well. Wearing these can make a huge difference when coming off a bike.
Yes, motorcycles are more dangerous than cars, and always will be. Yes, you have a risk of dying in a fatal accident, or seriously injuring yourself. But by wearing the full protection, you do seriously reduce your risk of injury. This does seem to be more of a UK thing - I rarely see people in the US wearing the full protective outfits.
If he loves it, the way my husband loves his bikes, I could never restrict him. His true passion is motorcycles - sports bikes in particular - and I am very lucky he does everything he can to protect himself while enjoying them.
ETA:
http://www.ntsb.gov/events/symp_mot...ing/liz de rome - lder consulting (paper).pdf
This research paper on the importance of protective clothing may be of interest. In particular, it points out that MOST motorcycle crashes are not the fatal ones here people keep referring to - most crashes do not result in fatalities. Hence the importance of protective clothing!