Theme parties are the bane of my existence. Any number of people come into Ellen Christine and ask for a "1920's" headpiece, or an Audrey Hepburn something. Most contemporary body types wouldn't like themselves as flappers, and couldn't carry off the deer-caught-in-the-headlights innocence that Miss Hepburn projected. To show them a beaded headband, trimmed in a spray of feathers, that we just happen to have on hand is usually a frustrating experience for me as an artist, and my assistants as salespeople. To wrap your head around a 1920's turban look, or a feathered accessory is difficult unless you're an actress, or an otherwise imagination-infused individual. Probably a warm up exercise should happen before people go out shopping , into a world they know nothing about, and can't easily grasp without a personal shopper, or a costume consultant.
Flexing the imagination muscle is helpful, so here's my advice:
when you're invited to a party with a theme, or a wedding with a theme, please do some homework first. Go to the library, a bookstore, or online for some basic description of what you're looking for. Then look at current fashion and see if anything out there looks like the images you're expected to mimic. In today's market, fashion reflects vintage mode, so it's usually easy to find a piece that isn't authentic or antique, but does lends itself to the era at hand.
Now you can go shopping. Ask for help, once you have a vague idea of what you want. Plan a budget, since beaded dresses can be expensive in any format......and every flapper worth their salt had a bead or two hanging around. Cocktail dresses and cocktail hats are the norm for a 1950's look. Sheaths work for a 1920's vignette. Feathers work with both of these looks, so always consider accessories your ticket to happiness. You may already own a dress or an outfit that could be perked up with a boa, or a headpiece, and the right jewelry, so check your closet, too.
Take heart, and be brave. Use those drama muscles and make it happen, and the theme of the party will be how fabulous you look!