<p>(In this answer I leave aside the strategy of "find questions you know the answer to and answer them" ... since I take that as sufficiently obvious to everyone.)</p>

<ol>
<li><p>A lot of unanswered questions could probably close as unclear, too broad, off-topic or duplicate. So can vote-to-close or flag (as appropriate to what privileges you have) when you come across them. </p></li>
<li><p>A lot of questions have answers or part-answers in comments. If you see a question that - between all the comments - seems to be largely answered, you should feel free to put together the relevant parts and post an answer. (If you're essentially just quoting a comment or two, you need to credit the author or authors, but I think answers in comments are otherwise fair game. Some other SE sites delete any comment that has <em>even a small part of an answer</em> as a matter of course; that's not how we work, but we could be a lot better about taking answers in comments to actual answers.)</p></li>
<li><p>A <em>lot</em> of new questions are really not clearly explained; anything you can do to encourage or guide new posters to produce answerable questions will help. (I expect many of us could answer more questions if the effort involved in getting a lot of our questions to a state where they can be answered at all were not taking so much time.)</p></li>
</ol>
