By Daniela (AD: websites mentioned)
I've been shopping (nearly) exclusively second-hand for my own wardrobe for over two years, Here are the shops I've used and liked in no particular order:
Vinted Vinted.com | Sell and buy clothes, shoes and accessories.
I've both bought and sold items on their German website, but they operated in a number of European countries. It's essentially like a big flea-market and I have always felt like a part of a big community. You buy clothes directly from their previous owners and can ask questions, haggle a bit (if you're inclined that way) and buy parcels to save on shipping. They have a buyer protection scheme too, but it is all private sales so you can't return the items (usually).
ubup momox fashion | Deutschlands größter Second Hand-Onlineshop für Mode & Accessoires
This is a German only shop (I think, though they sell through ebay too). Here you buy from a re-seller, so they do have a returns-policy. They have a wide variety of clothes and brands, so it is always worth a look.
Vestiaire Collective Vestiaire Collective : Kaufen und verkaufen Sie Premium- und Luxusmode aus zweiter Hand
The Classic! Your place for second-hand designer pieces. Prices can seem a bit steep, but they edit the pieces on offer too, so that you can be sure you're getting a proper designer item and not a knock-off. I've sold items here too and the service is great.
Here are some shops I've found and keep monitoring, but haven't bought anything from yet.
Rebelle REBELLE - Second Hand Mode kaufen
An alternative to VC, it also specialises in designer and high-end clothes. I sometimes compare prices between them and VC when I am looking for something in particular.
Wanderlust Vintage Wanderlust Vintage - Fine vintage and antique clothing (wanderlust-vintage.com)
A small selection of beautifully curated vintage pieces. The owner used to work in fashion and it shows. You can find some truly stunning and unique pieces at affordable prices. I have been lusting over quite a few pieces on here, but haven't found that one in my size.
Which sites do you frequent?