One of the things I recommend is for you and especially your passenger, to get on the bike the same way, from the same side every time, so that it becomes automatic for the both of you.
I have also taught 'The Ball & Chain' that if she feels the need to grab me, for an unexpected bump or to balance herself, to learn to grab my hips and not my shoulders, so that she is not hindering my steering inputs.
That she allows the bike to move underneath her rather than leaning one way or another works for the both of us, even at the Tail.
Also you want her to get on/off the bike without dinging up the saddlebags/side covers.
Mine was easy, as she has been on/around bikes for a good part of her life.
There are very few things in life as enjoyable as taking your girl for a spin on your Harley...