I brought my first passenger up last weekend. (Talked nicely to the Irish Aviation Authority and managed to get my PPL day after submitting application!)
Advice? Don't forget about your saftey briefing. It not only shows the pax what to do/not to do, but also sets the tone that safety is priority and you are very much in charge during the flight.
Also stick to an area you know. Don't want to get lost and frighten her too much!!
And advice passed on to me---bring a plastic bag in case she doesn't feel well!