I use org-mode for keeping track of invoices. I make them each a task, and give the tasks states such as FUTURE/INVOICED/PAID/LATE/RECEIPT; this makes it quite hard to lose anything.
The data for each invoice is kept in an org-mode radio table, and the invoice itself is generated from a org-mode source blocks. I "call" the invoice source block to generate the invoice, which is usually text but is occasionally LaTeX when the client really insists that they need a PDF. This result goes into a collapsible drawer, and I can easily save it out to a separate file. In fact, when the result is LaTeX it's possible for org-mode to process it into a pdf directly, although there are some quirks to be aware of there.
On the other hand, I don't use org-mode for keeping track of normal tasks much.
I found all of them to be too complex. I built my own editor plugin and command line tool that is super simple. The basic idea is to spend less time organizing tasks and more time completing tasks.
I currently use Workflowy. It is not FOSS but it is has some nice features. It syncs between devices, has a decent mobile client, works offline, seems to have a good developer, doesn't cost an unreasonable amount, has pretty good multi-user features.
Not really. I keep it as a backlog of shite to do and prioritize it all maybe once every few weeks. Pop a task off the stack, and push stuff into the bottom.
It is like a single person not really but kind of agile workflow. Works well enough.
The data for each invoice is kept in an org-mode radio table, and the invoice itself is generated from a org-mode source blocks. I "call" the invoice source block to generate the invoice, which is usually text but is occasionally LaTeX when the client really insists that they need a PDF. This result goes into a collapsible drawer, and I can easily save it out to a separate file. In fact, when the result is LaTeX it's possible for org-mode to process it into a pdf directly, although there are some quirks to be aware of there.
On the other hand, I don't use org-mode for keeping track of normal tasks much.