"If you wish to make an apple pie from scratch, you must first invent the universe. "

This is a really excellent set of guidelines on writing technically.

I think it really highlights the importance of writing for an audience rather than yourself.  I mean, you (presumably) already understand what you're describing. Share the love.  Consider the reader's interests more than your own.

Carl Sagan says, "It's not all about you."

By the way, have you all seen this?  The Carl Sagan one is also excellent.