Keep a record of your accomplishments and contributions from day one, including emails thanking you for your work, performance reports, and all positive feedback. When it's time for your performance review, if you're seeking promotion or negotiating a pay rise, you'll wish you had done it. So start now!
It's easier to go down the rabbit hole than it is to pull yourself out of it. And on the way up, you may stumble (literally). It took a helpless fall for me to take control of my own life -- and to speak up and fight for myself instead of sitting back and letting the drama floating around get the best of me.