If the question is good, but general enough to be off topic here, **don't**:

* Just close it, when it could be migrated to another site where it is on topic.
* Recommend asking on another site, unless closed, because [cross-posting is not permitted](http://meta.stackexchange.com/questions/64068/is-cross-posting-a-question-on-multiple-stack-exchange-sites-permitted-if-the-qu).

Instead, **do**:

* Flag for migration, in addition or instead of closing.
* If you recommend another site, tell the user to delete the question here first.