IS THIS ACTIONABLE?
You are asking yourself this simple question for all the stuff you collect. Is there something I can do about this NOW?
If the answer is YES...
... do it
(if you can get it done in 2 minutes or less)
You can decide if you need a bit more time ( 5 minutes) but the idea is to get stuff done quickly and not get bogged down in a huge project when you are trying to "clarify" you list.
... delegate it
(if it is NOT your thing to do or someone else must do it)
This will be more than just asking others to do your work or passing the buck. There are plenty of tasks you are responsible for but can't "do" on your own. You need to schedule a meeting but someone else has the authority to reserve rooms? This will become your "waiting for" list.
... defer it
(put this in a place where you will be reminded at the appropriate time)
Make a calendar event with a reminder to buy the theater tickets that go on sale next month. Have your phone remind you Thursday afternoon when you are picking your kid up from school to talk to the teacher about ???
You need these to be trusted reminders so that you won't spend the entire time between NOW and the EVENT worrying about what you are forgetting about. You make the reminder and forget about it until that "thing" pops back up into your vision.
If the answer is NO...
... delete it
(just trash it)
If it is not needed and not important. It is simply taking up bandwidth for you and causing yo stress. Throw it away. De-clutter your house, your office, and your MIND.
... file it
(if it is just reference material - simply file it away)
There are many, many systems for filing this reference "stuff". But whether digital or paper, you simply want to have system that gets this stuff out of the way AND still allows you easy access when you need it.
... someday maybe?
(this is the stuff you don't want to forget about, but you have no immediate plans for action)
This is one of the most compelling and useful ways to de-stress about your "to-do" list. You would likely be surprised how much unconscious bandwidth these things are taking up in your mind.
Write down your someday maybe list...
trip to Italy
clean the garage
hire a personal assistant
... and then quite worrying about it and trust yourself to come back and review this list as needed. At some point one or more of these will come OFF the someday maybe list and become a real project.