Is it too long? Look, nothing in the non-painful world is worse than a too-long reading. You have the combination of being a captive bored audience plus the building anger of "Who does he/think she is, thinking we want to sit through this much blah-blah?"
Is it too short? I am pretty sure that it is never too short unless it's so short that it's confusing (IE "Did she just run off the stage 30 seconds after coming on?")
Is it funny? Funny readings are way more entertaining than unfunny.
How are the eyebrows? Ideally eyebrows will be recently waxed.
What to wear? Need to look not-dumpy. Need to look not-dorky. Need to look not-too-hipstery, like that is ever a problem but still want to avoid looking TOO much like a "stereotypical writer." What does that even mean? Stop acting like you have THAT many clothes or are even that capable of pulling together "looks."
When in the order am I reading? The sooner the better in case I suck and people can then enjoy other people's pieces to get the bad taste out of their mouths.
Did you practice? I hate practicing. But that's stupid, you need to do it. I know. So what's your problem then? I don't know. This is why you were never a good musician, because you hated to practice. I know!
Who will be there? Basically this just applies to my parents so I won't be cursing up a storm in front of them. Otherwise don't really need to worry about whether I'll be reading my pro-abortion manifesto in church or my fundamentalist poem at the PFLAG meeting.
How drunk should I get ahead of time? Probably not very. But what if being the tiniest bit drunk loosens me up some? What should I drink then? Probably something clear.
No seriously, what do I wear? It's too late to go shopping, isn't it?