Digging a really worthy item out of a heap of old things is truly a talent. It takes knowledge, education, and years of practice to identify what period of time this or that thing comes from. There are some common features that are characteristic of clothes of the same periods of time. Study the history of fashion because it will be of great help to you in the long run. If you are a beginner and prefer online shopping, we suggest you use a Google Image search to see if the item you are interested in is visually similar to those that were made in those times. If you like it better to buy things in a regular store, do it only if you trust the seller. Remember, though, that sellers can also be mistaken since they are no fashion experts. But if the item and its price range satisfy you, then buy it.
You might sometimes hear that the piece if clothing is deadstock. It merely means that the clothing, although being vintage, has never been used or worn and still has a price tag on it. Such things can even be seen sold in batches if the store didn’t manage to sell of them out a decade or so ago.