Open & Closed Sort
Due to the fact that the majority of the stores inspected were poorly organized I organized card sort from the 75 items of stock to see how users would categorize them. These items were quite varied and even I was not sure exactly how to categorize them. 13 users were given a Miro board and asked to arrange the 75 items (yellow post-its) into categories (blue post-its) and told that an item could only go into one category.
This provided 5 clear categories that were persistent across the 13 users: Occasions, Table-top, Decorations, Balloonery, Fancy Dress. And although I was not 100% sure that balloonery was a word, google quickly confirmed that other party shops were using it also.
After I had the 5 categories, I conducted a second round of card sorting with the heading above and found them to be consistent in their sorting. From this, I decided that the categories were intuitive enough that a new user to the site could accurately find what they were looking for on the first try.