Recently I've seen two questions with improper tagging and poor question construction.
How can we as a community encourage each other to ask good questions and improve tagging?
For new users (15-30days on activity):
If this behavior persists and the user's getting too many closed question and DV. He/she could be banned from asking further.
In all cases ensure that the question is on-topic. If not, flag or vote for close. Specifying the reason (conditional).
Taking the above course will compel the user to change their style.
And as a general rule:
One should put in effort into the question, provide relevant information. Check and see if anything that would earn specificity to the question is added.
Add tags that are relevant to the question not just fill anything so that you can get the question through. If you find yourself doing that, there's a high chance that you didn't put any effort into the question. If you genuinely didn't find a relevant tag and are not allowed to create one. Then just tag anything. And leave a comment that you couldn't find a relevant tag so that some high privilege/experience user could add one.