I have found the most important thing is comfort. If she is cold or wet (feet and hands especially), she'll want to go in. So be sure she dresses for the weather. Bring something to eat and drink, and plan for a bathroom break. Some of the women I've hunted with were weird about doing their business in the woods. Other than that, keep it relatively short, half-day at most. Maybe an AM stand for a couple hours, a short walk to get the blood flowing and another short stand. Once she gets out a few times, she'll let you know whether she can or wants to stay out longer. Never know, she may end up wanting to go all the time and stay all day.