The Developer added these thoughts to the TaskPaper help file and they've let me use TP in a whole new way...
First I turn off most of the “visual interface” so that I have a very simple-looking text window.
To use TaskPaper effectively in this minimal mode:
For each big thing that I am working on I create a project. For example, I have a project for each of the applications that I’m working on, books that I want to read, and website work that I need to do. Right now I have about 30 projects overall.
I also have a default “Inbox” project at the top of my list. That’s where I put new tasks that don’t fit into an existing project. Later, when I have time, I’ll go back and figure out which project they fit in, or I’ll give them their own project.
I then add related tasks and notes to my projects. For well-defined projects (like a book list or grocery list) I just keep a simple list of tasks. For less-defined projects (like a software application) I also have many messy notes mixed in with the tasks. When I complete a task, most of the time I delete it (Command-K) right away. For tasks that I need a record of, I’ll tag them @done and then I’ll press Command-Shift-D to send them to the “Archive” project.
I don’t use tags very often, except for the @done tag and sometimes the @today tag. Other people use tags quite extensively, especially people who are following the “Getting Things Done” (GTD) style system. TaskPaper’s tags work well for assigning GTD contexts to your tasks.