It all started when I found a Gucci sweatshirt at Goodwill.

Amanda Samuel started collecting vintage at 16, doing community service at a Long Island Goodwill — where she found a Gucci sweatshirt in a garbage bag for $5. Twenty-four years later, she can date a garment by touching the zipper. This week: side seams, invisible zippers, pinking shears, and how to read a piece of clothing like a book.