If you’re thinking about using pay-per-click search ads (like Google AdWords), here is a great article on Search Engine Watch by Jeremy Hull about writing effective search ads. There’s a great snippet from Jeremy’s article that  applies to all advertising really, not just paid search ads:

“Ernest Hemingway once wrote a story using just six words, and is said to have called it his best work. The story, in its entirety: For sale: baby shoes, never worn. As a paid search advertising nerd, I can’t help but notice that this story is not only six words long, but it’s also just 33 characters. In less than half of the space allotted to a paid search ad, Hemingway was able to capture the reader’s imagination and evoke an emotional response. With twice as much room, we can surely compose an epic, or at least write some effective ads!”