Mike Davidson has an intriguing article on originality in logo design. His first paragraph says it best, so I’ll just quote here:
“Never waste a stroke.”
That’s the best piece of advice you’ll ever get in logo design. However, it’s also advice that can inadvertently get you in trouble. Draw a blue circle on the screen and you’ve just stolen the Blaupunkt logo. Draw a yellow line and you’re copying Visa. Draw a black swoosh and you’re ripping off Nike. The less intricacies involved in creating your masterpiece, the more likely it is that someone has already created it.