I am a bit tired of new (and not so new) users who bug you with additional questions in comments, do not bother to answer comments, and never bother to vote. They are not the only ones. Some older users often do not bother accepting an answer of upvoting good contributions to their own questions. The welcome comment we give in reviews is intended for new users. However it is seen by many older users and could be a good reminder for all of the way the site works.
I am personally sensitive to the way my contributions are taken. I do not mind being criticized explicitly, because I can either learn something, or teach something of both at the same time. But why should I work, why should I contribute, when no one cares? I mean, I sometimes write documents for myself, because I am interested, but I do not bother putting them online. At least I do not have to expect a reaction.
Our contributions may not be great, but they are work. I taught my children to say thank you even for a glass of water. I do not see why I should expect less from users of this site.
Below is the welcome comment I intend to use when reviewing the first post of new users. I may complete it with a comment on specific points raised by the question asked.
I think there should be a policy on this. And I am interested in your opinion.
My proposed welcome comment:
Welcome to Computer Science Stack Exchange. Since you are a new user, remember that the local way to show appreciation for contributions of other users, or for help received, is to upvote their post, question or answer, or accept the current best answer. You may downvote if you think it is more problematic than helpful (bearing in mind that answers are intended for all users, with varying competence). See https://cs.stackexchange.com/tour. When posting a question, make sure to give enough context, and show how you tried to answer it on your own, so as to be very precise regarding your problem.
Related question: What to do with users who aren't voting or accepting answers