1. Does it fit into the big picture?
This is the 80/20 rule. Should eliminate 80% of stuff. Of course you have to know what the big picture is. I think many people are afraid to eliminate stuff because it MIGHT turn into something useful.
2. Is it important or just urgent?
Some stuff is both! But in general, the more you do important stuff – the less stuff there is that is urgent but not important.
3. Am I the only person who can do this?
If the answer is YES in your business then you’re not doing well in building a company – just a job.
4. Do I have to be there in person?
I’m ambivalent about this one. Technology is good for transmittal of information without you being there in person. But lousy for the nuance of non-information, emotions, possibility, serendipity etc. Since you don’t know what you don’t know it’s hard to tell in advance.

[Digression about the phrase “You don’t know what you don’t know”

• There are things you know you know. This means you know the question and you know the answer.
• There are things you know you don’t know. This means you know the question but you don’t know the answer.
• Then there are things you don’t know you don’t know. This means you don’t even know what the question is. Or that you have a world view that frames the question in a way that’s not useful. Face to face meetings can teach you a lot about whether you and the other person share the same world view but only if you assume you might not.

– end of digression]
5. Will it cost me if I don’t go?
And what will it cost me (in opportunity cost) if I DO go? As the original article (see below) says the COST might be “who will I piss off if I don’t go?”

Questions from http://cashbulge.com/2007/08/14/a-few-tips-on-how-to-shrink-and-prioritze-your-to-do-list/
[The Comments are mine]