<p>I usually mark the question as a "<em>favorite</em>" if I want to be able to have some hope of (more) easily finding it again in the future. (See the image below.)</p>

<p>Another alternative is, of course, to bookmark the post in your browser. I tend to do this less often as I tend to find it more, well, tedious. But I do sometimes also use browser bookmarks, just a lot less often.</p>

<hr>

<p><img src="https://i.sstatic.net/JIbf2.png" alt="big, honkin' arrow pointing at the favorites button" title="Click the star to add the question to your favorites list"></p>

<hr>

<h3>Some additional suggestions</h3>

<p>I also stumbled upon the other options in the list below while I was looking for something else. I decided to mention them here. (If nothing else this might allow me to find them again later. ;-)</p>

<ol>
<li><a href="http://meta.stackexchange.com/a/13996/147712"><strong>This answer</strong></a> on <a href="http://meta.stackoverflow.com"><em>meta stackoverflow</em></a> also points out that each question has its own RSS feed which you can subscribe to if you wish. I found the RSS link obfuscated at the bottom right hand corner of the page. (See also the image below.)<br>
<br/>
<img src="https://i.sstatic.net/HGbv3.png" alt="big, honkin' arrow pointing at link to RSS feed"><br>
<br/>
This option is apparently not restricted to question pages. Many other pages on the <a href="http://stackexchange.com"><em>Stack Exchange</em></a> sites also appear to have RSS feeds available.  </li>
<li><a href="http://meta.stackexchange.com/a/86250/147712"><strong>This answer</strong></a> (to the same question) provides a reference to an App on the <a href="http://stackapps.com/"><em>StackApps</em></a> site which might be useful. 
<br/>
Note: I have not used any App from StackApps yet, so I have no idea if this is a good tool or not.</li>
<li><a href="http://meta.stackexchange.com/a/95519/147712"><strong>This answer</strong></a> appears to provide a good explanation of how to use your profile dropdown at the top of each page to sleuth out updates to your "<em>Favorites</em>" list.</li>
</ol>