Dancing-girl titillation in 1900 was a bit different from the "Live Girls!" of now. Showing off your petticoats was enough. Cause a scandal turn-of-the-century style with a bright tutu and tights contrasted with a somber black top and heels. Add feathers to your hair for more can-can seduction.
Toulouse-Lautrec frequently painted figures in flat colors. In The Japanese Diwan below, there's no detail to the woman's dress, but she still has plenty of form. This can be achieved with any well-shaped black dress; I picked one with strong shoulders and a plunging neckline. Don't forget to top off your outfit with a striking head piece.
This isn't a standard party look by any means, but the exposed bra, skirt fringe and lurid green are certainly inspired by the absinthe-soaked Dance at the Moulin Rouge. That skirt will give good shimmy for your shake.
Since Toulouse-Lautrec lived in a brothel, the ladies of the house were frequent subjects of his work. Let's forgo dressing like prostitutes in favor of mimicking the slouchy casual seen in Au Salon de la Rue des Moulins. Harem pants and a draped blouse are a must, but a hair wrap and no-nonsense flats say lounging is serious business.