Glad you’re on the page, @cardsandstitches.
Choosing the expense category for your transactions depends on its description and purpose.
QuickBooks Self-Employed offers a comprehensive list of categories you can choose from. You can refer to this article: QuickBooks Self-Employed Schedule C Categories breakdown.
Also, I recommend consulting an Accountant so you'll be assisted in choosing the right expense category.
I also added a link for your future reference that has a lot of information about organizing your QuickBooks account: Helpful articles.
It'll be my pleasure to assist if you need more help.