One thing I hear so much of is "vintage clothing won't fit me." Let's talk about this. It's a mistaken impression that all vintage is tiny. There's actually a lot of it that's perfect for more full figures. The 50s were very into voluptuous women, but they did like smaller waists so sometimes that can be tricky. Also a lot of 60s stuff is great on bigger sizes and they weren't as into the tiny waists by then. And even in the waifier decades, like the 20s and 30s there WERE plus size women and they didn't walk around naked. It's easier to find the smaller sizes because as a species we have in fact gotten bigger but also remember that a lot of the fit was due to restrictive undergarments, like girdles, and corsets if you go further back. But as a larger woman myself I'm always hunting for the bigger sizes in vintage, my eye is just naturally drawn to it. So don't hesitate to ask about what I may have in your size and don't let your build determine whether you can or cannot wear vintage. Even in smaller girls, finding vintage that fits correctly is daunting. It's always a matter of trying it out and seeing if it suits your particular body type. And there's always more vintage than just dresses. Vintage cashmere sweaters for instance, or bags, or coats.
Another thing to bear in mind is to always check the measurements in online listings. Do not take it for granted that what you see in a photo is the size of the garment. Most vintage sellers, myself included don't have a dozen or more dressforms to fit every size dress. We therefore pin larger garments onto our existing dress forms to make them fit and show them to their best. So if it looks like a size 6 it may in fact be a size 10, but pinned.