Here are a few tips from the Fitzgerald Press:

Be polite and courteous.
Make sure you know your script.
Know how to roll with the punches.
Build rapport.
Have all of your information resources in place.
Know how to use your databases, and how to toggle between them effectively.
Know your product or service.
Ask a lot of relevant questions.
Identify the customers’ communication style.
Control the call.
Make the most of each opportunity.
Make it happen.
Keep excellent records.
Maintain thorough communication with all departments.
Know your salesperson’s calendar.
Follow up with each customer in a timely way.