a few pointers i can share after 25 or so years of riding,
1. if shes a new rider explain shes the boss, we stop when you say stop, we pull over when you say pull over, we rest when you say we rest.
2. She should not fight the lean of the bike, explain you cant control the lean angle, the degree of the turn and your speed dictates that, leaning against the turn will only cause the bike to lean into the turn further.
3. Smooth shifts, radical shifting will only cause the front of her helmet to contact the back of helmet, with a little practice you can shift so smoooth your passanger will think your bike is an automatic transmission.
4. You must mount the bike first, brace yourself then have her place her left foot on the left peg, step up swing her right leg over find the right peg with her foot and sit down, i like to have my passangers mount from the left side as it reduces the chances of comming in contact with a hot pipe.
5. If you have a backrest try to get her comfortable using it as this will help her lean with the bike, if not have her scoot up to the front of the rear pad and hold your waist.
6. You must master and be comfortable with countersteering, first of all this should be the only way you ever steer your bike 1up or 2up. By using countersteering no matter what she does back there you will be able to make that bike lean and turn, and a slight tweak of the bar back and the bike will stand back straight up and go straight again.
7. explain to her that her feet are to remain on the pegs from the time she mounts the bike till the time she gets off.
I know this comment will draw some different views but here goes, I'm a firm believer if your going to go 2up you put the rear tire at max sidewall pressure and preserve the specified pressure split from front to rear.
example lets say the tire pressure spec is 32 rear and 28 front thats a 4lb split. lets also say the rear sidewall max pressure is 36 psi, when riding 2 up i would set the rear at 36 and the front at 32
Lastly riding 2up is by no means the time to show off, keep it to a nice low key cruise and she will take many more rides with you.
sorry about any spelling errors, im on my way out and dont have time to spell check or proof read