Marketers call it the 80-20 rule. It’s the peculiar phenomena where 80 percent of your business comes from 20 percent of your customers. But there’s more to this than meets the eye. People who spend a lot of money with you obviously like your kind of products or services. This means that they may also spend a lot of money with your competitors.

With a sensible mailing plan, you can convince your best customers to give you a greater share of their spending. Moreover, if you use your records to understand these customers, you can create a profile of them. Then create a mail program to attract more customers who fit the profile. They will become good customers, too. You might want to consider using a computer database for customer information. There are many off-the-shelf programs available and they make it very easy to analyze information and send personalized messages to the people in your files.

1. Give customers more of what they want
Go beyond the “Dear John Kopilak” salutation. Say you know John Kopilak’s shoe size and preferred brand. You can send him a letter when new shoes in the preferred brand come in. Let him know that you’ve set aside a few size 9EEEs for him to choose from.

2. Find new customers like your best customers
Are you doing a lot of business with 35 to 45-year-old men who drive American-made cars and live within 25 miles of your store? Rent a mailing list of other 35 to 45-year-old men who drive American-made cars and send them an offer.

3. Do more of what you do best
What sets you apart from your competitors? The answer might be found in your database. If you’re a caterer, you might discover that you get a lot of breakfast party business from mid-sized service companies. Knowing this, you can rent a specialized mailing list of mid-sized service companies in your area and send them a mailing that features your breakfast parties.

4. Get feedback
Out of sight is out of mind in business, too. Write customers to ask how they enjoyed the party you catered or the car you sold them. Simple letters like these help keep you top of mind and bring customers back.

5. Beat competitors to the punch
A clothing store can use its database to determine if it sells more camp clothes in late April than in May or June. With information like this, you can invite your best customers to private sales at these times, before your competitors run their sales.

6. See what works
Do you want to know what people are buying? What price are they willing to pay? Maybe you want to try selling a new item. Send private offers through the mail to your best customers. Maybe attach a coupon. Then see how many customers bring in their coupons. If something works, repeat it.

7. Use customer feedback
Knowing your customers is just as important as knowing your product. Enter customer feedback into your database and see what you can learn. If you’re a computer consultant, for instance, you might discover that complaints about one software program come mostly from people who also have another software program installed. Knowing that, you can address a possible compatibility problem and advise customers effectively.

8. Get more bang for your advertising buck
You may be advertising your sale in newspapers, radio or television. But when a customer gets a letter about sale items that specifically appeal to his or her tastes and needs, it’s something special. It’s a message that the sale is personally relevant. The customer appreciates the notice and spends accordingly.

9. Serve your customers better
Customers are more than happy to help you help them. Ask people what they want and what they need and put the information into a database. Then use the information to better serve your customers. For instance, if you have a jewelry store, you can note when customers buy birthday or anniversary gifts. You can even ask people if there are any special occasions that they need to keep track of. Then, when an anniversary or birthday approaches, you can mail the customer a reminder. You can even offer to help pick out a gift.

10. Let your customers know they matter
Use the database to find things that your customers want and need, then contact them with the information. Anything from a private sale to a reminder that the car is due for a tune-up is good customer service.

11. Reactivate inactive customers
If someone hasn’t done business with you in a while, send the person a discount coupon. It reminds them of your business and may help spark a renewed business relationship.