I like 2 rules I have learnt in practice in this area. Follow them+improve day to day and you will get great outcomes, measurable in $$$ or whatever currency you fancy.
Rule 1: Pareto 80:20. 20% of your unhappy customers will create 80% of your problems. Try to keep at your customer at their maximum level of satisfaction at the limits you can. Put customers first and better to say: put yourself in their shoes and constantly ask yourself "will I buy again from this company?", "how quick the problem is solved?", "how responsive the seller is?" etc. You are having customer experience on your own. Look for the best way of finding a win-win situation or win-lose (lose for you as a seller in this case) to solve your customer problem. Happy customer brings positive feedback and increases your sales by coming back or advising your offers to their friends etc.
Rule 2: be the best adviser and consultant. Be reliable consultant that offers best goods/services that suits and never try to sell something they don't need. People buy from people they trust. Build the trust and reliability and this will lead to the long lasting relationship.
And some other tips I found useful from this article:
1) Answer your phone.
Get call forwarding. Or an answering service. Hire staff if you need to. But make sure that someone is picking up the phone when someone calls your business. (Notice I say "someone". People who call want to talk to a live person, not a fake "recorded robot".) For more on answering the phone, see How to Answer the Phone Properly.
2) Don't make promises unless you will keep them.
Not plan to keep them. Will keep them. Reliability is one of the keys to any good relationship, and good customer service is no exception. If you say, “Your new bedroom furniture will be delivered on Tuesday”, make sure it is delivered on Tuesday. Otherwise, don't say it. The same rule applies to client appointments, deadlines, etc.. Think before you give any promise - because nothing annoys customers more than a broken one.
3) Listen to your customers.
Is there anything more exasperating than telling someone what you want or what your problem is and then discovering that that person hasn't been paying attention and needs to have it explained again? From a customer's point of view, I doubt it. Can the sales pitches and the product babble. Let your customer talk and show him that you are listening by making the appropriate responses, such as suggesting how to solve the problem.
4) Deal with complaints.
No one likes hearing complaints, and many of us have developed a reflex shrug, saying, "You can't please all the people all the time". Maybe not, but if you give the complaint your attention, you may be able to please this one person this one time - and position your business to reap the benefits of good customer service.
5) Be helpful - even if there's no immediate profit in it.
The other day I popped into a local watch shop because I had lost the small piece that clips the pieces of my watch band together. When I explained the problem, the proprietor said that he thought he might have one lying around. He found it, attached it to my watch band – and charged me nothing! Where do you think I'll go when I need a new watch band or even a new watch? And how many people do you think I've told this story to?
6) Train your staff (if you have any) to be always helpful, courteous, and knowledgeable.
Do it yourself or hire someone to train them. Talk to them about good customer service and what it is (and isn't) regularly. (Good Customer Service: How to Help a Customer explains the basics of ensuring positive staff-customer interactions.) Most importantly, give every member of your staff enough information and power to make those small customer-pleasing decisions, so he never has to say, "I don't know, but so-and-so will be back at..."
7) Take the extra step.
For instance, if someone walks into your store and asks you to help them find something, don't just say, "It's in Aisle 3". Lead the customer to the item. Better yet, wait and see if he has questions about it, or further needs. Whatever the extra step may be, if you want to provide good customer service, take it. They may not say so to you, but people notice when people make an extra effort and will tell other people.
8) Throw in something extra.
Whether it's a coupon for a future discount, additional information on how to use the product, or a genuine smile, people love to get more than they thought they were getting. And don’t think that a gesture has to be large to be effective. The local art framer that we use attaches a package of picture hangers to every picture he frames. A small thing, but so appreciated.
If you apply these eight simple rules consistently, your business will become known for its good customer service. And the best part? The irony of good customer service is that over time it will bring in more new customers than promotions and price slashing ever did!
.. and keep in mind: