Don't. Waste. Time.
When it comes to efficiency/effectiveness, I prefer to focus on "Do" instead of "Don't".<p>Richard Hamming (from "You and Your Research"):<p><pre><code>  1. What are the most important problems in your field?
  2. Are you working on one of them?
  3. Why not?
</code></pre>
<a href="http://www.paulgraham.com/hamming.html" rel="nofollow">http://www.paulgraham.com/hamming.html</a><p>Paul Graham's (from "Good and Bad Procrastination") generalization of Richard Hamming:<p>What's the best thing you could be working on, and why aren't you?<p><a href="http://www.paulgraham.com/procrastination.html" rel="nofollow">http://www.paulgraham.com/procrastination.html</a><p>edw519's generalization of Paul Graham:<p>Work on the most important thing until it's not the most important thing any more.<p>I have developed this excellent/horrible habit of not being able to focus on very much of anything if there was something more important hanging over my head.<p>Excellent in keeping me from trivial pursuits. Horrible at meal time, bed time, other people time. I'm still a work in progress.