To achieve a good customer service, your company must have good representatives in the field. You need to train your employees well since they are the ones who represent your company in the eyes of your customers. You need to train your employees on how they should handle customers and respond to their inquiries.
Tell your employees that the phrase "I don't know" is illegal to be delivered to your customers, yet replace it with something like "I can get the information for you" and not to fail what they have promise. Teach your employees to never reject what a customer requires even though what s/he require is beyond the employee's knowledge or responsibility. When that happens, tell your employees to direct the customer to the right person to answer his/her concern.
Customers need a feeling that the company's employees have interests in their problems and have found every way possible to solve it. Therefore, never imply that the solution that your employees offer is the only way and they have no choice but to accept it. Avoid the phrase "This is the only way" and use "The best option is..." instead. This phrase brings positive meaning that will meet customers' expectation for options and alternatives.
Enthusiastic employees are also a positive point to your customers. Your employees need to show that they enjoy their job and are ready to help whenever your customers need them. Do not show the faces which consider that customers are troubles, but greet them with best smiles and friendly words like "What can I do for you?" However, do not overdo the enthusiasm or it may feel fake to your customers.