As we round the corner to 2016, everyone's looking for ways to build upon 2015's successes or overcome its failures. What everyone really wants is an advantage -- an unfair advantage -- something that sets us apart from the crowd and gives us an inside track.

And customers are the key. You have to bring back the old ones as well as make the most of the current ones.

While all that might sound obvious, what isn't obvious is that not all customers are created equal.

Research indicates that acquiring a new customer costs at least five times more than retaining a current customer. Also, returning customers spend, on average, 67 percent more than new customers.

This means current customers are the most reliable sources of recurring, bottom-line building revenue. Unfortunately, many companies ignore their current customers in an effort to drum up new business. 

Make no mistake: new client acquisition is a key component of a successful business. But client retention is the foundation of a sustainable brand.

So what are the keys of building a thriving, customer-driven business?

1. Make Them Feel Truly Known

Today's customers have an overabundance of choices and will happily dump an impersonal brand for one that pleases them with personalized offerings.

However, customization goes beyond just changing the name of the subscriber in your email subject line. You need to "develop a customer DNA" by digging deep into their interests, preferences and desires. A truly personalized experience is tailored for one person.

"The key to driving higher sales is to understand your buyers' purchasing behavior," says Obinna Ekezie, the CEO of Wakanow.

This means utilizing innovative e-commerce solutions like Fanplayr that analyze what "digital body language" to not just segment customers in real-time but create custom offers and calls to action. Maserati -- the famous car brand -- did exactly that and, by taking over 50 attributes of their visitors into account, was able to increase their average conversion rate by 28.4% and their net-revenue per visitor by 54.6 percent.

This also means being responsive and available. For instance, BoldChat recently surveyed 4,700 consumers and found that of consumers who "prefer live chat," 47 percent were more likely to make a purchase following a live chat conversation.

Zopim by Zendesk is one solution that helps companies interact with their customers live. Zopim's in-depth analytics let you easily rate and track existing customers, a practice which is essential to the next key.

2. Rate Them Ruthlessly

Every customer must be treated with respect. But not every customer is equally desirable.  According to Gartner group, 80 percent of your revenue comes from just 20 percent of your customers.

Indeed, some people are just inconvenient drains who are not worth the effort required to keep them. Many businesses are afraid to prioritize their customers because they don't want to alienate anyone or something they think would hamper their profitability.

This is, however, a misguided mindset.  It just doesn't make sense to pour a ton of resources into customers and products that are not good for your business.

In order to identify and nurture your most dedicated clientele and maximize your return-on-investment (ROI), you need to carefully calculate the value of your leads and customers.

Be smart about allocating your time, money and energy in order to improve your bottom line and make your best customers feel special.

3. Delight Only the Best

Once you have identified your brand evangelists, you need to sweep them off their feet.

As  author and sometimes Inc. columnist Josh Linkner puts it, "The same principles that make us fall in love with each other can be deployed for your business, as long as you do it in a thoughtful, authentic, and (of course) loving way,"

This focus on love translates into finding creative means to celebrate, engage and thank them.

Start simple by offering special discounts and loyalty programs. Follow up by asking for feedback; include your best customers in your product creation and testing phases. Invite them to one-on-one events. Encourage them to share their experiences on social media. Always apologize for your mistakes and make adapting to their needs a top priority.

In all, court your favorite customers: listening and responding to their invaluable suggestions will only vastly improve not only your services and reputation, but your profits. 

"Love the one your with ..."

The success of your business is directly proportional to the love of your existing customers. In fact, companies that prioritize their current customer experience a spike of almost 60 percent in their profits.

The secret is to know which clients to favor for maximum productivity and profitability. By getting to know them, weeding out the resource-drains, and focusing on only the best, you will be able to build deeper relationships with the customers who consistently show their love for your brand.