If you are like me and you love thrift shopping, every time you travel you're gonna look for new thrift shops. Trouble starts when you have no time for wandering around new city and exploring all the small shops. After all, you want to see more sights, take more photos, eat delicious food, shop in other stores and that leaves you with little time to explore thrift shops. 
When I was in Prague all the stores I found online were in different parts of the town. It may seem possible to visit all of them, but if you are staying for only couple days you can do it only if you dedicate a whole day to thrift shopping. I know, it's not easy. 
My advice is to find couple of stores that are close to each other and visit them on your way to a museum or restaurant. That way you won't miss much of sightseeing but you'll still be able to do some shopping. The street to go to in Paris is Rue De La Verrerie with two second-hand shops located almost right next to each other. Also, Pompidou museum is just one street away so you can visit the museum first and then do some shopping. Don't go shopping first, it's hard to walk around the museum with hands full of bags. The two stores are Free'p'star and Kilo shop.

Free'p'star is your normal thrift shop, and you can find really nice clothes here! I bought delicate 80's blouse for only 5 euros! They have furs, leather jackets, silk shirts, vintage dresses and simple jeans. The only reason I didn't buy more clothes here is that my suitcase was already dangerously heavy and I hand no more room for all the lovely stuff I wanted to buy. Special edition to this store is upstairs where you can go through a bin full of clothes where each piece is only one euro! If you like hunting and digging until you find that perfect piece of clothing this store is definitely right up your alley.

Kilo shop is a store with unique concept. I first heard of it from my friend who went to Kilo shop in Amsterdam and was thrilled with the whole idea. Each piece is marked with a badge in different colour. You need to find a kilo of stuff with the same badge colour and then you pay one price for the whole kilo. Kilo of clothes marked red is 20 euros, green and yellow 30 euros and orange 60 euros. Some clothes has fixed prices, those marked blue will have unique price and white badge means a piece is 3 or 4 euros. There are scales all over the store so you can measure your pile of clothes at all times. It all sounds complicated but it gets clearer once you are in a store. This type of shopping is perfect for more people shopping together because you can actually gather enough clothes for a kilo and the split the price. Well, I actually could find a kilo of stuff I liked but, like I said, my suitcase just couldn't handle an added kilo of clothes. Kilo shop in Rue De La Verrerie has a variety of clothes, here you can find anything from amazing colorfully African dresses and long Japanese kimonos to simple black turtleneck dresses. If you love thrift shopping you should definitely visit it, even if you don't end up buying anything you'll still have fun.