Customer acquisition is an ongoing challenge. You need customers for your company to survive, but converting them is costly. What to do?

I use the Pareto principle to evaluate customer strategies. Twenty percent of clients generate 80 percent of revenue and profits, so those are the customers you want to invest in. It's more lucrative to market to existing customers than to focus solely on recruiting new ones.

Be Everywhere With Omnichannel

Great marketing strategies are built around data, and existing customers provide you with plenty of that. If you've been documenting your customer interactions, you should have a picture of who they are, what types of products they buy, and what their pain points are. You can use that data to build personalized marketing strategies that keep those people interested in your company.

To nurture your existing customer relationships, you need to meet your audience members where they are. And when it comes to digital touchpoints, they could be anywhere. That's why omnichannel marketing strategies are essential in today's selling environment.

Omnichannel means delivering a strong brand experience wherever your customers find you. Customers might first encounter your brand through a social app on their smartphones, then browse your products on a tablet, and finally, convert after seeing an email from you on their desktops. As the relationship progresses, they might connect via Instagram, Snapchat, and on-site chat programs. A good omnichannel strategy guarantees you'll be there to engage them regardless of how they choose to interact.

Here's how to use omnichannel to build ongoing customer relationships:

1. Build your foundation with traditional media.

Research shows that 87 percent of people use multiple devices simultaneously. Someone who watches your commercial on her smart TV might Google your site on her smartphone while she continues enjoying the show. So, it stands to reason that you need a presence on both traditional and digital media.

Ora Organic, which sells plant-based, all-natural supplements, saw enormous success after it was featured on "Shark Tank" in February 2017. Sebastian Bryer, Ora Organic's CTO and head of growth, reported that the company collected tens of thousands of prospects' emails during the episode's airing and generated hundreds of Amazon reviews within three months. The TV spot led to high engagement rates on other platforms, which is the ideal omnichannel engagement scenario.

In our streaming-centric age, you may want to get the word out by placing commercials on popular content sites as well. Identify which streaming services your audience members prefer and buy airtime there. For instance, you might place an ad with Spotify if that's where they listen to music or on Hulu if they're fans of shows like "The Mindy Project" and "Difficult People." Not only will you pique new prospects' interest, you'll also stay top of mind with existing customers.

2. Keep the conversation going through social.

Monitor any mentions of your brand on social media. Respond to as many comments as possible, whether they're good or bad. Thank someone for a shout-out, crack a joke with them, or reshare their content -- any one of these is a great way to build customer rapport.

If someone criticizes your company, respond thoughtfully. Answer the complainer's questions and show that you take constructive feedback seriously. Negative reviews are great opportunities to persuade disgruntled customers to give your company another try, and your attentiveness could inspire them to become brand evangelists.

3. Personalize your marketing messages.

By using data on customers' browsing and buying habits, you can recommend products they're likely to want or need. Customers will appreciate that you're looking out for their interests, and your marketing team won't waste time targeting the wrong people with the wrong products.

Most personalization strategies can be automated via computer algorithms, so you can scale these tactics as your company grows. For instance, Spotify delights customers by sending them curated playlists of new songs they might enjoy. The playlists are built by algorithms that analyze each user's listening histories, making users feel that Spotify really gets them.

4. Recommend complementary products.

Once a customer purchases a product, you can predict what else he might buy. Someone who purchases fitness equipment may also be interested in energy bars. Likewise, a person who buys skin moisturizer is likely to purchase other beauty products. By suggesting additional relevant products, you provide a valuable service and give them reasons to continue buying from you.

You can also drive up sales by offering bundles of similar products. Pep Boys does this by offering free tire rotations with every oil change. Customers appreciate the convenience of the extra service, and it makes them more likely to come back to Pep Boys for other car-related needs. Amazon also employs this strategy by recommending related items to increase the number of units per transaction.

When customers abandon a product or check-out cart, email them a coupon to entice them back. Or if you know the abandoned item will be on sale in the coming weeks, let them know that, too. The value of that specific sale will be lower, but the customer will so appreciate the tip that she'll be even more inclined to shop with you in the future.

The customer relationship is no different from any other. If you want people to keep visiting your site and buying your products, you need to give them a reason to stay engaged. By nurturing your existing customers, you increase their lifetime value to your company -- and develop a strong brand reputation in the process.