Use hierarchy whenever appropriate, try to group the messages by:
Modals (e.g. about.foo, jump_to_note.foo)
Don't duplicate messages that are very widely used.
One such example is aria-label="Close" which should go to a single message such as modal.close instead of being duplicated in every modal.
On the other hand, don't overly generalise messages. A close message that is used whenever the “Close” word is encountered is not a good approach since it can potentially cause issues due to lack of context.
If you see multiple messages joined together only to apply add a variable such as a user-inputted value, try to join those messages together into a single message containing a variable.
So instead of “Number of updates: “ + numUpdates + “.” use $(t("number_updates", { numUpdates })) where the message translation would appear as Number of updates: {{numUpdates}}.