definately lots and lots of grooming...try to make her as beautiful as you would if you were to bring her to an International Competition. You want her coat to look great, but you also want it to look like her real coat.
Be as honest with the people...I wouldn't use Show Sheen because it gives the horses coat a shinier appearance than what it is.
I'd definately be prepared to get on Ginger and ride her before their daughter does. Most people want to see the horse go through the gaits (walk, trot, and canter) before they decide to ride the horse.
When I was horse searching, the owners had to get on their horse and put it through the gaits (walk/trot/canter and whatever else it can do). One lady said there was no need...and I told her that whether there is or not I would like to see the horse in action, she refused...so I told her that I was greatful for her time and that I hope she finds a good buyer for that horse...and I walked.
Also I'd definately save tacking up, and even cleaning the feet till they are there. As a buyer they'll want a horse that won't kill them when they tack up, nor will try to kill them when cleaning their feet.
I'd lunge her a little bit to get her "funnies" out, but not to the point where she's tired...I'd want the prospective buyer to know the horse with as much energy as she has without lunging.
Also, make sure her stall is clean, and everything that she'll be in/near is fairly clean...a good clean barn always gives a good impression.
Do let us know how it goes!!!