Before my wife rode on the back for the first time I told her:
Make sure I acknowledge you are getting on or off before you do it.
Keep your feet on the footrests unless getting on or off.
When I turn left look over my left shoulder, when I turn right look over my right shoulder.
I can feel every time you move around back there.
She has been a great rider from day one.

Also, it will take time for you to get used to the extra weight high and back, it does effect balance at slow speeds or at a stop.

 

Two things I caution a passenger to do is let me know before they get on or off and to be careful not to kick the saddlebags. Other than that, issues can be addressed if and when they occur. Some females are perfect passengers and aside from their breasts pressed into your back you'll hardly even know they're there, others not so much.

I'm not married so I've had different passengers over time, and the worst thing about passengers, in my eyes, is the time I have to spend polishing the scratches out of my bike after the ride. Most (not all) chicks just don't get it when it comes to keeping paint looking nice.

 

My wife has been the perfect passenger since day one. Besides the previous suggestions I just told her to be "one with the bike". In other words just be relaxed and go with the bike.

 

Don't rush your wife. Nothing personal, but I wouldn't trust my life to someone who has only been riding a big touring bike for 2 months. Have you been practicing panic braking? There was just a thread from someone who crashed his Streetglide, because he skidded when he had to panic brake.
I took the Skilled Rider's Course after riding 7 years, 20k on a Vulcan 750. Because I knew my new to me FLHTCUI was much harder to stop fast, without skidding. Ride a few more months, then take the SRC.
Do it right, so your wife is happy, and you can really have fun touring 2up. It is a huge responsibility though.

Good luck.

 

I was hoping that someone would say this. You need to be a very good rider to be competent with a passenger. Get some miles under that bike before you put your wife on it.

 

Having a willing passenger is important. Knowing that you can handle a passenger is equally important. 5K on the limited should have made you comfortable solo.

Do you know anyone who can be a passenger for practice rides, maybe an empty parking lot

 

Like others have said tell her to stay still when you are going slow. In turns tell her to look over your shoulder of the direction you are turning. The instructor in our safety class that we have to take in Texas told her that and it works great.

If you have any of these type classes where you are take her and that will really help. She will have an idea what it takes to ride a bike and that works well. Who knows she may even learn to ride in the class. My wife totaled a little 250 in the class. She hit a light pole. She did get on another bike but was too scared to try it again. She flunked but makes a great passenger.

 

Or tell her to close her eyes and just relax when turning.

 

I tell them get on and off only on the left side and only when I tell them to. I explain to them about how their body movements can mess me up. I also tell them to lean with the bike. I start off extra slow with passengers until their comfortable

 

Tell her to imagine that her nipples are glued to the back of your jacket. THat usually gets them to sit still! Seriously, all the good advice has been given above.
I had a (large) friend who is a bike instructor to ride pillion for an hour, and he demonstrated the effect that a pillion passenger has on the bike - mostly by doing things like leaning round to talk to me while in a curve! Buiult my confidence really quick, did that...