For absolute minimal structure, I would recommend at least one folder where new notes are created (set in settings). I call mine “_inbox”.
This is handy for two reasons. First, often new notes are raw and you don’t always have time to “finish” them. Second, because new notes are more likely unfinished and untagged and unorganized and unlinked, it’s easy to lose them.
Start new notes in a folder and move them out ASAP.
I would also recommend one tag to identify notes you know you need to go back and work on. Some people use #todo or #seed. I use #touch to ID notes I know I need to go back to.
This helps with notes that are good enough to move out of your inbox into the growing population of other notes. You don’t have to wait for a note to be perfect before you move it out of the inbox. You can still find it later.