A one-person business does not need more tools. It needs fewer places for work to disappear.
My stack is built around simple rules: every task has a next action, every idea has a capture point, and every repeated process should become a checklist before it becomes a problem.
The tools change over time, but the principle stays the same. I choose software that reduces coordination cost because, when you work alone, coordination is still real. It just happens between your current self and your future self.
The goal is not to automate everything. The goal is to protect attention for the work only I can do.