I have a four point instruction set for newbie pillions:
Keep your feet on the pegs
Don't touch the muffler because it gets hot
Lean when I lean
Hold on
Anything else?
don't shift around to get comfortable mid-turn
-Brace yourself against braking forces by squeezing thighs together, and if need be, a hand on the gas tank.
-Wait for the rider to OK mounting and dismounting, every time! Do not skip this step, it will save a bike tipping over and a back/hip being strained trying to hold it up.
-Talk with the pilot and decide if snuggling up is preferred for both of you, or if a little space is better.
Watch the "lean" advice, you don't want them contributing to the lean or fighting it, they should try and remain nuetral, just stay with the bike.
Advice for the pilot: Check tyre preasure, and be aware that chain could tighten and it riding in the dark, the headlight angle could be higher and most of all yours brakes, you will need to use both brakes more than when solo and breaking distance will increase, try and stay smooth with brakes and acceleration. Under some circumstances, on hills etc, gearchanges feel a bit different, possibly something to do with the chain?
Advice for both, enjoy yourselves.
I advise any riders to put their head on the same side as the turn (turning right, put their head to the right of mine), and to generaly keep it from being directly behind mine. This prevents slamming of helmets on up/downshifts, and allows me to sit in a more neutral position with my head up.
Hold on to the rider, not the grabrail in back.
get a bike of your own ;)
do not dig your nails into the side of my jacket every time we accelerate or turn.
Give them a summary of the planned route.
Give them a few moments with their seating position.
Give them a good idea that if they don't pay attention, both of you will end up in a serious amount of pain for a serious amount of time.
Give the throttle a 'blip' when you're about to leave a light, stop sign, whatever. (The wife has caught on quite well to this). It allows for them to look around at stops, and know when acceleration is coming.
Make up simple hand signals:
thighs squeezing = "I'm hangin on, lets rip!"
stomach squeeze = "Hi, I'm still here and paying attention"
bangin on the ribs = "I need to pee, drink, eat, dropped something, caught a bug, etc"
bangin on the ribs ONE SIDE = "LOOK OUT" (usually a suv, minivan, or cellphone about to cream us)
Reach back and smack her on the ass now and then. If I need to explain this one, you need more help than gstwins can provide.
Also, if she likes a gentle swerve on country roads, she'll let ya know. It's usually a giggle or movin a little closer.
I ain't teachin everything here ;)