I agree with what most have said in this thread regrading safety. Personally I rather ENJOY taking passengers!
1) I always start by giving the person a lecture on the risk and safety involved.
2) Then I hand then all my spare gear, helmet, jacket, gloves, shin/knee protectors and I make sure they know to wear at the very least a pair of good jeans and good high boots to protect the ankles.
3) I then demonstrate riding techniques while the engine is off, so I can show them handling differences their weight can make. I further remind them NOT to shift their body weight and to keep their feet on the pegs at ALL times unless they are dismounting from the bike. This includes mounting after I give them the ok, and dismounting after I give them the ok. Another reminder is to ALWAYS follow my upper body position at ALL times and NEVER lean in the opposite direction of me; especially while in a turn or else theres a chance I won't make the turn and we could crash. Hopefully enough of this sort of talk and reminders and having a little quiz before we take off helps to get their mind ready for fun, but not forgetting the dangers involved should they do something wrong while on the back. Sometimes while on a straight rode I will purposefully have them shift their weight slightly so that they can really see just how much their lean can change my steering input.
4) I have never thought about asking if they have health insurance, it never came up, but in hindsight, all those I did have as passengers DID have it and if they did not, I probably would have thought twice before taking them.
5) Techniques I change.... I brake much earlier and softer so I do not get passenger slap hehe or crushing my manhood on the gas tank! FAIL! I also attempt to accelerate slower so as not to have them feel they will fall off, additionally I explain that I will REV the engine prior to acceleration so that they have a queue to be ready. I found that riding 2up actually improved my riding and helped me become better at turning and many other things simply because i was unable to get my body off of the seat. I tend to lane split passenger or not, however its just a matter of doing it at a slower speed but this creates a problem with sudden steering input sometimes needed when lane splitting.
Oh yes and I have a speed hump on my jacket... EVERY passenger HATES it lol because they CONSTANTLY hit it and have trouble moving their head around it, however I have NEVER had a single helmet kiss! Sometimes I think wearing the jacket without it, would be better... but I dont because I always wear my 2-piece and refuse to swap safety for the comfort of the passenger.