(I shouldn't need to point out that this is all very tongue-in-cheek and you can wear your damn dress any way you please)
Surly teenager face and slouch. Check. Yeah, I'm really a lumpy middle aged housewife, but just use your imagination, okay? I was the surliest of surly teens once upon a time and that experience has served me well as I now chase kids off my lawn.
Strapless bra-because it isn't 1979, and gravity has taken a toll. If you're still perky (or just don't give a damn) treat the bra as optional. Ditto the undies.
"Hmm, I really ought to get that mole on my arm checked...anyway...
I hear you-it does get cold indoors with that constant air conditioning! Under no circumstances should you wear your slip dress over a shirt (or god forbid, a polo neck). That's not a slip dress, that's a pinafore. You'll look idiotic unless you are in fact wearing a slip, or a vintage nightie, in which case you'll just look eccentric which is different in the very best possible way. Otherwise, resist the urge to follow the fashion pages and just wear something over your dress. I also tried a long waistcoat the same length as the dress and it looked great (forgot to get a photo, sorry). So to recap: Over, not Under. Got it?
...but go for a lightweight bag to compensate.
Vintage slip dress-good heavens I've owned it so long I have no clue where I bought it, or if I nicked it from a roommate.
Esprit rayon jacket-mid-80's, Marshall Field's, probably
Shoes-K mart a few years ago (like ten)
Vintage Philippine-made straw bag-New Life Thrift
Bracelets/rings/earrings-here and there
Fragrance-Vintage formulation Chamade
I gave serious consideration to wearing a long-line girdle, but that's really not in the spirit of a slip dress, and I just don't give a rat's ass if anyone doesn't like it. I'm not eighteen (thank god, I wouldn't want to go through that again) and a few lumps and bumps along the way are fine with me. It was hot and humid today after all that rain, and the thought of squeezing myself into spandex wasn't terribly appealing. You do what's best for you. My menopausal thermostat isn't having it.
Just make sure you bring your best surly teenager face.