What about a red rose corsage-type thing, pinned onto the dress at the neck or hip or wherever you like, and a red necklace? That way you wouldn't actually be doing anything to the dress, but your overall look would be more fancy. Are your flowers red? What about a big swatch of dark red satin hanging from the bouquet, either looped up to a bracelet round your wrist or just hanging to the floor? Or red ribbons/flowers in your hair? Or red ribbons looped around your upper arm somehow?
The skirt looks slightly transparent - you could wear a red satin sheath underneath and it would show through a little. Or a white petticoat trimmed with a red ruffle, that would peep out when you walked. Or you could make a dark red shrug/shawl/bolero to wear over the top.
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