Here is what Emily Post says about attire for black tie formal wear: Women Formal (floor length) evening gown Dressy cocktail dress Your dressiest little black dress Men Black tuxedo jacket and matching trousers Formal (piqu or pleated front) white shirt Shirt studs and cuff links Black bow tie (silk, satin, or twill) Black cummerbund to match tie, or a vest Dressy braces to ensure a good fit (optional) No gloves Black patent shoes and black dress socks In summer, in the tropics, or on a cruise: White dinner jacket, black tuxedo trousers plus other black tie wardrobe You can find their full guide to attire, from Casual to White Tie, on their website
Size Range: UK4-UK16 Materials: 70% wool, 30% silk When in doubt, stick to florals
check the size guide before choosing your size
Classic LBDs work well for summer days, cocktail parties and dinners but will likely not be appropriate for very formal occasions
I match fabric drape to the skirt volume, and I match fabric stability to the bodice support plan, because the halter neckline needs clean edges and predictable stretch