On the flip side, if you loved your job, your coworkers, your boss, the cappuccino machine, everything about the place, don't write page upon page waxing rhapsodic about all that you're giving up by leaving. A brief, heartfelt compliment to the company, or a thank you, is fine.
Or meet up with said colleagues at an industry event, because the world is awkwardly small. So it's in your best interest to make sure that your resignation letter is clear, concise, and polite. Here are some best practices you can follow to make your big exit a professional one.