Wearing something old with the clothes that are new provides the freshest looks on the streets of Paris this season.One rarely sees a well dressed person in head-to-toe costume of the current season but rather an electric mix of periods and styles that results in a passing parade where two people never look - not even a little bit - alike.

When Paloma Picasso does a mix it can start with a white spencer jacket from her wedding costume by Yves Saint Laurent worn with a vintage (2-year-old) taffeta blouse, also from YSL, plus a classic cut of Cerruti pants that she has always worn.

But for many of the young people on the street, the newest addition is often the oldest piece they can find in the flea market, perhaps a fragile blouse, a leather jacket, spindle-heel shoes or an array of jewelry.

Nothing, of course, is worn as it was originally intended. Glitter scarves once mad up for evening are paired with tweeds; shoes for dancing show up with anklets, earrings can be worn as pins.

Florence Mollien, a student, finds the flea market about the only affordable place around Paris, and spends what is left over on buying good shoes. Her stockings that look like Thierry Mugler's leg gloves (Mugler is her favorite designer) are really panty hose with the feet cut off. "I could never afford the original," she says, smiling.

Paolo Vincente, a model, mixes what he wears as a model in the fashion shows, particularly Courreges, with what he finds at Marche aux Puces. On his feet are basketball shoes sprayed gold.

Ex-model Brigette Jeanmaire is partial to the designs of Chantal Thomass, whose purple knit costume she was wearing last week onthe Boulevard Saint Germain. But with it, she had mixed a bit of Dorothee Bis, including that designer's rolled brim knit cap. Her friend, art dealer Zoran (he doesn't use a second name) was wearing a gold suede jacket, light gabardine pants, gloves, a shoulder bag, no tie. "Never a tie," he insisted. "For no business or social occasion would I wear a tie. Ties are finished."

Janine Gatson, a hostess at the Ministry of Finance, would buy mostly Thierry Mugler designs if she could afford them. But since that is hardly the case, her selections are a mix, including a leatehr blouson jacket, a copy of Claude Montana's corduroy pleated front trousers from Initial and a silk scarf she has had for years.

Students and sometime model Dominique Eveque, 18, picks up parts of her wardrobe all over Paris. One day she was wearing a man tailored tweed jacket from Georges Rech, sweatpants she found in a boutique in Les Halles, cutout shoes b Sacha and the tailored leather shoulder bag that many women carry in Paris.

Corinne Pitay found her American made jacket with the Puritan label in the flea market, the printed challis skirt she made herself. But the rest of the garb she was wearing while reading a book at a cafe on the Left Bank was bought at good boutiques.

Cotton is the essential criteria of clothes Laure Brasilier D'Hauterives buys, mainly because classrooms at the Institute of International Relations where she is a student are kept warm. So she is partial to Indian cottons from the shop Mohanjeet and vintage cotton blouses from street markets.

Palace dressing is the way Ducloux Nathalie describes her style. "I'm always looking for funny shirts to wear to Palace (the disco)," she says. She scouts out shiny fabrics, particularly satin and bright colors, especially red. Mostly she looks in the flea market. Her latest finds - pointy stiletto heel shoes from the 1950s that she wears with anklets, and fragile drop earrings. At the price she could afford, none of the earrings were in pairs, so she wears them as pins.