If you're looking for some foolproof flow chart that will instruct you and the rest of the community about what to do for each and every question like this one, then, sorry, you'll be disappointed in this answer. The process isn't all that simple, and every circumstance provides its own teachable moments. 

If you feel like a question could or should be improved, you have all of these options available: 

* **Leave a comment**. Explain how the question could be improved, or post a link to helpful guidance found in our Help Center or on ELL's meta site. 
* **Cast a downvote**. This is one way you can indicate that you feel the question needs improvement.  
* **Cast a vote to close**. If the question is put on hold, the intent is for the OP to make improvements so that it can be reopened. 
* **Look for a duplicate question that has been satisfactorily answered**. In the case of your example question here, there's a good chance someone has already asked a similar question that might provide a useful answer for the OP. (Hint: Tags may help you do this.) 
* **Flag the question**. This action will bring the question to the attention of the moderators. 
* **Edit the question and improve it.** Sometimes it's easier to show a person how to write a better question simply by improving their question and adding some additional details. (This isn't always possible, but sometimes it's a viable option.) 
* **Answer the question**. Yes, I know that there is a meta question about not "feeding the bears." Nevertheless, sometimes even a poorly-posed question can get a useful answer and everyone can learn from it. 

However, that being said, I'll offer the following caveats: 

* **Respect views that differ from your own**. You might see a trivial question that is easily resolved by consulting a grammar book, while someone else may see an interesting question about an issue that has vexed them for a long time. Don't expect that everyone will view the question in exactly the same way you do. 
* **Always be constructive in your feedback**. Try to nudge people toward improvement, not just for their particular question, but for the community as a whole. Avoid put-downs, and abide by the Code of Conduct. 
* **Understand that newer users are probably unaware of community expectations**. Before admonishing a user too severely, take a peek at their profile. How long have they been a member? How many questions have they asked? Is the problem you are noticing a first-time problem, or a recurring problem?
* **Avoid being too legalistic**. Barrack-room lawyer tactics often sow seeds of discord and animosity and rarely help the site improve over time. 

Lastly, when moderators see a question flagged, they have the same options available as the rest of the community: comment, downvote, edit, answer, or close. (However, when a moderator votes to close a question, the question is immediately put on hold.) You said in your question that you've sometimes flagged a question but nothing has happened. This may be for a few different reasons: 

* **The moderators haven't seen your flag yet**. We are not on duty round the clock. We are busy people who may go a whole day or two without checking in. 
* **The moderators agree with your sentiment, but decide the issue isn't bad enough to intervene.** Sometimes we simply elect to defer to the will of the community. 
* **The moderators are discussing the issue among themselves**. Sometimes we don't feel comfortable acting unilaterally, and will wait for a second or third opinion from someone else on the mod team before deciding upon the best course of action. 
* **The moderators disagree with your assessment**. Occasionally, a question will get flagged, and not only are we unsympathetic to the voiced concern, but we flat out disagree with it. 

With so many people having so many options available, there is no single, cut-and-dried "best" response to a question that perhaps ought to show more details, or may seem too basic, at least on the surface. 

Some of our members see themselves primarily as helpful teachers, and they aren't comfortable downvoting or exhorting people to adhere to some elusive standard. Others want to see the quality of the site maintained, so they may be a little quicker to cast a close vote, or to write a comment pressing for more detail to be added into the question. Personally, I'm thankful the site has such diversity, and I think the system works best when we appreciate each other's strengths rather than focusing on each other's shortcomings.