The important thing is to make sure that people understand that a closure is not permanent, which is why questions are given the "[on hold]" suffix rather than "[closed]".
On Robotics, one of my Copy-pastable comment text for common problems with questions? is:
Questions by new users for closed for other reasons
Welcome to *robotics* XXX, but I'm afraid that questions like this really aren't a good fit for a stack exchange site. We prefer *[practical, answerable questions based on actual problems that you face](http://robotics.stackexchange.com/help/dont-ask)*. Take a look at [ask] and [about] for more information on how stack exchange works. Also, the [*Robotics* question checklist](https://robotics.meta.stackexchange.com/q/1302/37) has good advice on how to write a good question. If you edit your question to fit our community guidelines we can reopen it for you.
Closure is intended to temporarily stop people answering questions which can't be easily answered in their present form, while the question is being improved. As such, I disagree with tbm0115's suggestion that we should artificially delay closing a question (at this stage in the sites life there aren't enough people closing questions as it is) and suggest that we always close a poor question as soon as possible, but give people the information they need to fix the problem.
Instead, I offer the following suggestion:
- If you want to vote to close a question without writing a comment to say why, with suggestions as to how to fix the problem, think about how this looks to a new user and how they might feel about the rejection.
If people assume there is nothing they can do about their question being closed, and this drives them away, then we should do all we can to correct that misunderstanding, encourage them to learn how Stack Exchange works and ask better questions.
Finally, don't forget the importance of broken windows theory.
The quicker poor questions are closed, the higher the good:bad question ratio is, the more likely new users will see examples of good questions, and the less likely that they will base their own question on a poor example of a question. This is why good questions are the most important thing on a new site. They draw in experts to answer them and they set a good example for how new questions should be framed.
So, close early, close often, and comment with the information needed to get the question re-opened.