What I’ve learned is quality over quantity. If you build a good wardrobe where anything can go well together you will have endless of outfit options that you can rotate around!
• for basics, I usually recommend searching for second-hand stuff on Vinted. Definitely try finding cotton, people there sell good quality basics for 2-3 Euros. As someone here already mentioned, try favoriting things you like and find pretty so the algorithm learns what you’re interested in.
• the one thing I always recommend to invest in is good jeans, you can find excellent pairs second hand of course — I like to buy them new so it’s easier to keep them in good shape. Stores I frequently buy my jeans from are Hollister and Urban Outfitters. They’re great especially with sizing and my favorite pairs I’ve had since about 2-3 years. If you want cheaper options, Bershka, Pull&Bear and Stradivarius are great as well. They come out with new stuff all the time and I think especially Stradivarius is really timeless.
• For fancier stuff: If you go on vacation, I love to check out little boutiques that have unique pieces. I’ve bought tons of dresses and tops in Zandvoort during my last vacation that are still amazing quality and I don’t usually see on anyone else. Also, thrift stores and flea markets (if you have any good ones near you) often have a few hidden gems that don’t cost much.
• I don’t think shein or polyester is bad, for me personally cheap clothing just makes people smell bad. If you have a good find the material really doesn’t matter, at the end of the day body hygiene is much more important.
I recommend searching on Zalando, About You, Asos, sites like that. There’s tons of brands and a lot of things to search through. I know you’ll eventually find things you meant for you!
Last tip: Look for clothes on Pinterest that lay flat instead of being worn by someone, then figure out what you believe would suit YOU best. Try image search on different online stores or through Google Lens and you can find a lot as well!