Consider keeping your shoes, bag, and other accessories neutral and classic so that they don’t “fight” with the dress. While the red dress will be something everyone remembers, you will be able to use the accessories again and again. Decide which colors flatter your skin tone.
The “little black dress” is a style staple, but it is more common for cocktail, not formal (black tie/white tie) events like prom. Should you choose a short black dress for prom, you will probably want to choose something which is simple and chic, because you will undoubtedly be wearing the dress again and again, for all different sorts of events. Look for a style you can dress up for prom and other formal occasions, perhaps with stockings with rhinestones or seams or patterns, with unusual shoes of any color, and with a suite of elegant accessories: evening bag, shrug, jewelry, and your flowers. You can dress it “down” with simpler accessories for openings, concerts, and dinner out on the town. You can also jazz it up for clubbing.
If you choose a full length black dress, you may want to consider getting one which can be shortened into a “little black dress,” such as a streamlined gown with an unusual neckline or back, but with a relatively simple waist and skirt.