<p>Oh, I should tell you about this link: </p>
<p><a href="http://www.artofproblemsolving.com/Resources/AoPS_R_A_HowWrite.php%5B/url%5D">http://www.artofproblemsolving.com/Resources/AoPS_R_A_HowWrite.php</a> </p>
<p>It's more geared to writing solutions to math competition problems, but some of the principles are general.</p>