first of all congrads! it took me (her actually) awhile to get her to do that but now we really love riding together even though it is kinda cramped. i actually really love the new backrest. the DHL track should drop off her new HJC CL-SP helmet today
the technical preparation - set correct ammount of shock air pressure (if i understand rigth 10-15% pounds of air for total weight above ~150 pounds. someone correct me if i'm wrong). when adjusting the air pressure remember that the chambers in the shok are tiny and very small ammount of air is required. every mesurement with presure gouge yu make will loose you about 5 lbs of pressure. i usually put more then needed and go down from there but make sure not to exseed the maximum value - some say 70Lbs, others 45lbs. i play it safe and never out more then 30 in first place. even if both of you are lighter peps DO set your rear shocks to 4th position. i would not touch the tire pressure at all.
before the ride explain to your SO the correct way to mount and dismount, epmphasise that you need to be aware of her intent to mount or dismount so she doesn't try to jump of as soon as you stopped. ask her to look into the turn and lean with you (later stages you can try to let her lean even more then you for faster corners)
your first ride take it slow (kinda obvious
) while you at straight line feel how the acceleration and braking responce SIGNIFICANTLY changed. leave plenty of manuvering room as you make your first turns - during one of the rides my friend had a first time passanger that just refused to lean whatsoever cousing ugly wide turns. i will just have to brag that my wife is simply amazing passanger rider (deemed by my riding friend as well) - when we turn sometimes i forget i have a passanger at all
take it slow and you will be fine.
also i would like to remind that passanger needs all the protective gear as well, not just helmet. we got my wife pair of real motorcycle gloves during winter sale on newenough.com (10$ for 60$ msrp ones!) but it could be something cheaper, heavy-leather work gloves for example untill you get something more comfortable. riding jacket is a must too, for now my SO wears my old jacket which fits her much better then me anyways, she really wants a leather one but untill she finds her jacket this one will do. sturdy footwear (at least over the ancle hicking shoes) is also needed.