A number of times recently I've seen a new user drop a simple question (some bad, but some OK questions), and it's got some misunderstanding of what they're working on or a confusing explanation, either of the question itself or the work done. Now that question could be improved (maybe even self-answered) if the user would only stick around and read comments.
So - is there a way to advise users that they should check back every five minutes or so for comments and other responses? Maybe in "How to ask a good question"? While giving such advice in a comment is still worthwhile, it's often not getting read fast enough to improve save-able questions.
If this advice already exists, it probably could benefit from a little more prominence.
Added: Perhaps as observed there is shyness or language issues holding some new users back - the issue of (apparent) non-engagement is the same though. Now I wonder whether we need to make sure that new users know that comment responses would still be viewed favorably as engagement. We shouldn't expect question-level standards of language or precision in comments, even though we may also urge them to clarify and expand the question itself as needed. One point here is that established users need to make sure they do not appear hostile to such comments (while still pressing for detail if needed).
As a side observation, if I am debating on whether to vote a question up or down, new user engagement will often weigh on the positive side.