We use Basecamp a lot at Orbeon, and we love it. Basecamp is simple, which is most cases means that there is a default way in which things work, and you can't change it. The beauty is that Basecamp gets the default right, most of the time.
Message categories are unfortunately one of those times where the default isn't right. When you start a new project, Basecamp provides 3 categories: Assets, Code, and Miscellaneous. Then when you create a new message, it picks by default the first category in alphabetic order: Assets. More often than not, this is not what you want.
So here here is what you can do; after creating the project:
- Remove the Assets and Code categories, if you don't need them.
- Create any category you might need (such as Issues, Releases).
- Rename Miscellaneous and add dot in front of the name (.Miscellaneous).