One item, one page
A vintage shop is not a catalogue of products with sizes. It is a list of single objects, each with its own measurements, its own wear and its own price. Treat every piece as one product with a stock count of one, and the listing closes itself when it sells. Nobody pays for something that went yesterday.
Write the measurements flat, in centimetres, in the description: chest, waist, length, sleeve. A buyer who trusts your numbers does not ask for them, and the ones who ask anyway are asking about something you left out.
Photograph the flaws on purpose
A missing button, a faded seam, a repair at the cuff. Photograph each one close, and say what it is. This sounds like it costs sales and it does the opposite: the returns and the arguments come from the things a buyer discovers after the parcel arrives, not from what they agreed to when they ordered.
Three photos carry most pieces: the whole garment flat, the label, and the worst flaw. Add one on a body if you have someone to wear it.
Drops beat a permanent catalogue
Vintage sellers who post a weekly drop do better than the ones who add pieces one by one, because a drop gives the audience a reason to open the shop at a known time. Announce the hour in your channel, keep the shop button as the way in, and let the pieces go in the order people order them.
What happens to the pieces that do not sell
Leave them up for a second drop before you discount. A piece that nobody took in week one often goes in week three to somebody who was not there the first time. Cutting the price immediately teaches your buyers to wait, and then everything sells late and cheap.
When you do discount, change the price on the page rather than announcing a sale. Quiet price changes keep the shop looking like a shop and not like a clearance rail.