I live next to Paris so i can give you some good addresses if you come to visit Paris. There is a lot of intersting shops....
Best places for shopping:
Le Marais:
-a lot of secondhand shops: Freepstar 8 rue Sainte Croix de la Bretonnerie and 61 rue de la Verrerie, 4ème; Studio W, 6 rue du Pont aux Choux,3ème; a shop named Vintage in Rue des Rosiers
-designers shops and multibrand: AB 33, 33 rue Charlot 3ème;
N°60, 60 rue Charlot, 3ème;
Olga, 45 rue de Turenne, 3ème;
Shine, 15 rue du Poitou, 3ème);
Joy, 38 rue du Roi de Sicile, 4ème;
Emilie Casiez, 57 rue Charlot, 3ème
ANAIM, 21 rue du Pont aux choux; 3ème
And a really cute tea room/shop: Le loir dans la théière, 3 rue des Rosiers, 4ème with old furnitures, many.
Palais Royal/Musée du Louvre:
American Apparel, 31 place du Marché St Honoré
Colette, 213 rue Saint-Honoré
Gabrielle Geppert, 31 galerie de Montpensier, Jardin du Palais-Royal, 1er: a beautiful vintage shop
Pierre Hardy, 156 galerie Vallois, Jardin du Palais Royal: amazing but expensive shoes
Marc Jacobs, 56-62 Galerie Montpensier, 34 rue de Montpensier
107 Rivoli, 107 rue de Rivoli, 1er: the Musée de la Mode bookstore
Rue de Rivoli with H&M, Zara, Bershcka, André....
Saint-Germain: beautiful shops, lot of art galleries
Le Bon Marché, 24 rue de Sèvres: a multibrands and a luxury store (like 5 floors of fashion brands) with amazing designers (Chloé, Chanel, Marni, Prada, Marc Jacobs, Balenciaga and many more...)
Allison, 3 rue de Buci, 6ème: a little shop with lovely brands like Maje, See by Chloé, Paul & Joe sister etc...
Vanessa Bruno, 25 rue Saint Sulpice, 6ème
Les Prairies de Paris, 6 rue Pré aux Clercs, 7ème
Taschen, rue de Buci
Nanie, boulevard St Germain
Isabelle Marant, 1 rue Jacob, 6ème
Mellow Yellow, 16 rue Saint Placide, 6ème: shoes, shoes and shoes (but little store)
Haussmann/Opéra: le Printemps (the designers and the shoes floors are amazing!), les Galeries Lafayette. The H&M store of boulevard Haussmann is big and great, but there is a little one too in Passage Provence, just behind le Printemps.
Les Halles: the Forum des Halles is a little bit shabby and dirty, but next to it, the area is better and there is some interesting shops: Kiliwatch, 64 rue Tiquetonne (a big store with books, second-hand clothes and shoes (a little expensive) and Royal Cheese (Cheap Monday, April 77, Sessun, Levis...) 24 rue Tiquetonne
Near to that store, there is a great street named rue Montmartre with amazing shops at the beginning of the street : Territoire (small designers from France), Maje, Les Petites, Manoush, Bérénice...
And Also:
Come on Eileen (second-hand clothes), 16/18 rue des Taillandiers, 11ème
Chez Mamie, 73 rue de Rochechouart, 9ème: second-hand and vintage clothes
Mamie Blue, 69 rue Rochechouart, 9ème: same things
Wochdom, 72 rue Condorcet, 9ème: vintage clothes (beautiful place, really 70's with vinyls, dark carpet, a bed in the middle of the room...)
I think i forget some adresses....