I believe there are 5 basic and easily followed traits and actions that can help your customer service employees to be top customer service personnel.
Passion
This is a must and most basic and often referred to as "fire in the belly" trait. If your customer service employee enjoys what they do, they will naturally feel motivated, appreciated and rewarded for it, somehow monetary rewards become less important. It will come naturally as a consequence of the passion they have and the satisfaction of doing it to make others' happy. Obviously this means you got to spend enough time recruiting the right candidate for the job and not just fill vacancies simply because you needed someone to sit at the reception.
Hard Work
Effort and hard work equal to results and cannot be ignored. Customer service is a lot of hard work for it takes a lot to please the variety of customers you may have day in day out.
Practice
Practice makes perfect. There is no short cut for doing the task yourself to gain a firsthand information and experience. Always encourage your staff to role play and use real case studies from complaints, feedback and compliments to stimulate the thinking process.
Focus
Know the limit of your resources to serve your vast customer base. Be realistic in setting expectations and not expect your customer service employees to run around to do everything within a short period of time. The best policy is still under commit but over deliver.
Build a service culture
Don't just enforce procedures and shouting instructions to get things done. Make your culture one that serves something of real value. Encourage your customer service employees to connect with people by communicating with everybody from customers, customer service employees, business partners and even with you as their employer. Get your customer service employee to communicate with the aim to delight and not to antagonist people. Accept and encourage feedback be it criticism, complaints or compliments. Encourage learning via mistakes for only through mistakes can your customer service employees grow, learn and improve.
Remember should you want to know more, click on my blog What Is Good Customer Service for more articles, analysis, discussion and video on what make a customer ticks.