1. Don't get involved in petty gossip. Stay neutral or stay out of it. Make this your personal policy and stick to it. That doesn't mean you can't be cordial, it just means you can't get involved in petty jealousies, nosiness, etc.
2. Stand up for yourself. Otherwise, you will keep getting stepped on and you will not be able to put an issue to rest. This includes anything from being mistreated to an unreasonable workload. It also includes a light workload and the desire to do more.
3. Learn how to prioritize. Staying organized helps you do this. Learning how to manage your workload with Microsoft Outlook or other tools keeps you from the feeling of having lost control, a major stressor in the workplace.