How should I give upvotes to questions?

I tend to upvote on the clarity of the question:

• Does it lay out the context of the question precisely but succinctly?
• If it mentions an error, does it give details?
• Does it contain code to reproduce the problem, ideally in a short but complete program?
• Does it ask a specific, answerable question?
• Has the questioner paid attention to spelling, grammar and formatting? (i.e. is the presentation good?)

Then about the question topic itself:

• Is it interesting and unusual?
• Does it surprise me (e.g. showing a bit of C# doing something I wouldn't expect it to)?
• Do I think other people ought to know more about this area?

• If you see yourself asking the same question - upvote it +1.
• If you don't know the answer for this question, and you would like to know - upvote it +1.

My suggestions...

• If the question is helpful to you, upvote it.
• If the question isn't clear or helpful, don't upvote it.
• If the question is a duplicate, don't upvote it. Upvote the original instead (if you find it helpful).
• If the question is "not very important", silly, off-topic, etc., don't upvote it. You may even want to downvote it.
• Most importantly, don't just upvote because everyone else is. There are already too many people who upvote nonsense questions.

In addition to many other suggestions, upvote a question you answered. Most likely, if you decided to invest your time into answering, the question was worth it, wasn't it?