Good question, and I'll preface this by saying it's _excellent_ that you care about responsibly casting close votes.

While we do have objective(ish) guidelines for close votes, it can be a judgement call at times. Also, there's also the [Raiders of the Lost Downboat](https://chat.stackexchange.com/rooms/3877/raiders-of-the-lost-downboat) chatroom where you can get input on specific questions. Sometimes it's requested there that a question is closed, or perhaps that one is reopened. There's absolutely nothing wrong with using Meta, but it's worth being aware of.

In terms of lacking sufficient information... it depends. If I see a question that is unambiguously unanswerable and would need a lot of work to make answerable, it should probably be closed as Needs Details or Clarity. Depending on the question, it might be better to close it as a duplicate of [a Canonical Question](https://meta.askubuntu.com/questions/3053/what-are-common-canonical-questions-for-our-site) (if there's an applicable one), as that can provide _some_ information for the OP.

On the other hand, if there's a question that's very close to having enough information, I'll probably refrain from casting a close vote. At the same time, I don't know if I'd _vote to keep open_, though. A good way to think about it is by considering if a question is answerable. To quote [this answer](https://meta.stackexchange.com/a/238416) by [Sam I am says Reinstate Monica
](https://meta.stackexchange.com/users/181798/sam-i-am-says-reinstate-monica) on MSE:

If you can imagine a potential answer

>  - That is unambiguously correct (I.E. the OP gave you all the information you need, and the answer is not an opinion.)
>  - That doesn't leave loose ends. (This covers the problematic list questions where there can always be more items to put on the list)
>  - That can be written without an unreasonable amount of effort
>
> Than the question is probably answerable.

If it's _close_ to having enough details and you think OP will add them (i.e., because you're in a comment thread with them), I'd be hesitant to VTC. IDK if I'd vote to keep open, though.

We have a reopen queue, too. If you see something closed, and the OP edits it to have enough details, you can vote to reopen. But... while this works in theory... new users can get discouraged when their questions get closed. This isn't intended to _blame_ those casting close votes. OT questions _should be closed_. But... if it's close to being answerable... consider if it's better to close or try to get the OP to add details. To be clear, there's absolutely cases where the right answer is to close it, of course.

Also... if you're not sure, there's _absoultely nothing wrong_ with doing <kbd>Skip</kbd>. If you disagree, it's also fine to ask here on Meta or [in Raiders of the Lost Downboat](https://chat.stackexchange.com/rooms/3877/raiders-of-the-lost-downboat) (although please include reasoning - simply stating that something was closed and it should be re-opened with no reasoning is... not great).