The biggest thing is to treat your phone interview as if you were going to a real interview. Get dressed up in your interview clothes and find a professional setting to interview from. Your attitude will show through the phone call, and being dressed in professional clothing will help you project a more professional attitude. Answer every question like you are in an in-person interview; if you need a moment to think of an answer, for example, say so and take the time to construct a good answer.
The idea isn't to be the most qualified person for the job. The idea is to be the most charismatic, the most likable, and the best fit for the team. Project your personality into the phone call, while remaining professional.
Here are some phone interview tips from a recruiting professional at Matrix: