Man, no wonder you guys don't vote enough, you're seriously overthinking things...

1. vote up questions you think are good
2. vote down questions you don't think are good

The tooltips are just that: tips. They're not definitive, legalistic definitions of when you must up or downvote, they're just short summaries of the most likely reasons you'd consider a question to be good or bad.

I may come back and add more later, but this really shouldn't need a long answer.

Man, no wonder you guys don't vote enough, you're seriously overthinking things...

1. vote up questions you think are good
2. vote down questions you don't think are good

The tooltips are just that: tips. They're not definitive, legalistic definitions of when you must up or downvote, they're just short summaries of the most likely reasons you'd consider a question to be good or bad.

Looking at the other answers, my thought process for voting up is similar to voretaq7's: if it's clear what they're asking and I think it's useful to myself or another professional, that's good enough.

For downvotes:

• When reviewing, I routinely click on the questions I think are bad and downvote them (if they're not already) so that if they do get closed the auto-delete process will nuke them. But since unanswered closed questions only need -1 for the auto-delete to get them, there's no need to vote them into oblivion.

• Redundancy between votes and closing is a feature: you want to close the really bad questions, but in the meantime you want them appropriately downvoted to show that they're bad.