Customer retention is a major focus among the data-driven marketers of today's biggest brands. Just ask customer retention "expert" Taylor Swift.

Related: Yes, Believe It: Taylor Swift Is a Customer Retention Expert

In fact, today's marketers are investing more time and marketing dollars in cultivating customer retention, as part of their role helping businesses to generate revenue from customers, both existing and new. Their reasoning: Customer retention is the right bet for a healthy and sustainable company.

Research backs that up. According to Bain & Company, increasing customer retention rates by just 5 percent increases profits by 25 percent to 95 percent.

So, what customer retention tactics are data-driven marketers from leading brands adding to their marketing tool box these days? And which companies are employing them? Here are seven examples.

1. Build trust.

Trust needs to be earned, especially when it comes to interacting and developing a relationship with your customers. In today's world, where every customer is bombarded by information, product placement and ads for myriad products and brands, trust is more important than ever. Once lost, it’s hard to gain back.

So, providing "social proof" from customers of your products' and services' quality -- in the form of online reviews -- is a great way to not only win new customers but reassure existing ones that they’re in good company.

Another way to build (and maintain) trust is to be transparent with customers. Everlane, for example, is a brand that produces durable bags and clothing; it shares all of its cost structure with its customers. By doing so, Everlane educates customers about its mission and builds trust along the way.

Treating customers with respect and keeping them informed when crises happen motivates customers to appreciate your honesty and remember your brand when they make their next purchase.

2. Add real value.

Let's say you have a great product or service to offer. But, are you adding enough value to keep your customers engaged? Adding value beyond features and benefits helps keep customers from moving to competitors offering similar products.

Take Apple: In a crowded PC market, Apple built a product that stood out and became the best-known computer company in the world. How did Apple do this? Instead of focusing on product features, it added value for customers by making its products easy to use. So easy, in fact, that most customers don’t even read a manual when setting up their machines.

So, add value to set yourself apart and keep your customers from jumping ship to a similar product. We can't all be Apple, but as marketers, our task is to know why our products are unique and to help our customers understand why those products add real value to their lives.

Related: Customer Retention Is No Accident -- How Small Business Can Get It Right

3. Don't be afraid to show your personality.

When your customers describe you, do they describe you as a person or an obtuse corporate entity? This is why showing your brand’s personality through your messaging and communication is key. An example of a brand that does this well is Dollar Shave Club.

Dollar Shave Club got started in 2012, with a humorous video. The video has since gone viral and helped launch a successful brand that many of us love. Through its content, packaging and customer service, Dollar Shave continues to stay true to who it is as a company, showing its personality, humor and wit -- which speaks well to any company's target audience.

4. Listen attentively.

Listening to your customers is one of the best ways to keep customers from leaving you! Listening to both good and bad feedback from customers will give you a better idea of what customers really want and need from your brand -- and give you ideas on how to provide it.

Data-driven marketers, then, need to stay informed about the reviews and feedback their customers leave, whether that feedback comes through a call center, tweets (or other social media channel), emails, etc. It is critical that they listen, and attentively, so they can address customers' concerns accordingly. That tactic will go a long way in customers' minds.

5. Surprise and delight your customers.

The secret to any good relationship is to keep your partner guessing -- and I sometimes wonder if that also applies in business relationships!

So, in the effort to surprise and delight your customers, ask them to take part in product testing; send them promotions on special occasions (think beyond the birthday concept -- and maybe celebrate something like the anniversary of when they became a customer). Let customers in on exclusive “behind the scenes” information. Just make sure that your gestures are there to engage and interest your customers, rather than merely advertise sales.

6. Build loyalty.

Loyal customers are the key to retention, and there are multiple ways to build a loyal customer base. First, however, you need to give customers a reason to remain loyal.

For example, anyone who has purchased from Zappos knows that the company gives customers the VIP treatment, reasoning that treating them well will pay off in the long run (which is right!). Other companies have also realized that strong loyalty programs and perks build loyal customers: Starbucks has a great program that not only keeps customers coming back, but lets them track and manage their "rewards" stars (points) on their mobile app -- a brilliant move, considering that a majority of Starbucks' customers utilize that loyalty program-on-the-go.

7. Don't skimp on customer service.

No matter how great your product is, if your customer service isn’t up to par, you’ll never be able to keep customers. According to Kissmetrics, 71 percent of customers surveyed said they had ended their relationship with a company at some point due to poor customer service. Good customer service means quickly taking action (both reactive and proactive) and communicating with customers on their prefered platform.

For example, if a customer reaches out to you on Twitter, make sure your first interaction also goes out through a tweet or direct message. Customer service is where your brand can really shine, when you set and beat customer expectations.

In today's noisy market, data-driven marketers who understand how to retain their customers will succeed. Customer retention marketing is the most cost-effective way to impact the bottom line of a business. By focusing on adding value, personalizing customer experiences and listening to their customers’ needs, savvy marketers are keeping more of the customers they’ve worked so hard to acquire.

They're showing that we can all be successful, like Taylor Swift.

Related: Why Small Businesses Should Be Utilizing Customer-Loyalty Programs