is to ask the lady. She probably has a few outfits that work for her and if you go with one of them, you will be assured of a good look. After all, she has chosen it to show her at her best.
Nurse, office worker, cheerleader, naughty schoolgirl, Betty Page look (vintage lingerie), waitress (cocktail or diner, depending on your preference), or just dressed to the nines, as you suggest. Nothing better than having a lovely package to unwrap.
But since not every outfit will work for every woman, and you probably do not want to get into a negotiation over who is paying to buy an outfit she doesn't already have, it is best to just discuss it, see what she has, and choose the one that sounds best. Works even better if it is an outfit you see in her gallery that attracted you to the lady.