Long-term clients are the bread and butter of a successful marketing agency. While it’s certainly a good idea to always be working on ways to bring in new business, it’s those long-term clients who are going to help you build a strong and sustainable portfolio — especially if you’re running a small or mid-size firm.

Not convinced that long-term clients are more valuable than shiny new ones? Consider that just a 5% increase in your firm’s customer retention rate can increase your profits by 25-95%. Add to that the fact that it costs five times more to attract a new client than to keep an existing one on board and it’s pretty clear where you should be focusing your efforts.

Knowing that long-term clients are important is one thing though — actually retaining them is another. Here are five marketing strategies your firm should employ to attract clients with long-term potential and keep them coming back for more.

1. Know exactly who you’re looking for.

Your ideal clients — and the ones who are going to stick around — are the ones who are looking for the exact thing that you excel in. Maybe that’s lead generation or conversion-boosting email marketing or social media or a whole other host of marketing-driven services that companies need if they’re going to succeed. Likely, it’s more than one of these things.

Defining what you’re best at will help you hone in on who the clients are that will benefit most from what you have to offer. From there, you can target them directly. You should be able to answer a number of key questions about your preferred clients, including how big they are, how much they have to spend, and what their biggest pain points are. You’ll narrow down your pool of preferred clients, but you’ll be able to attract those who have the most to gain from your services.

2. Celebrate the small (and big) stuff.

Marketing is all about goal setting. So when you meet or exceed your client’s goals, that’s a big win for both of you, and definitely something worth calling out. Celebrating achievements is a great way to keep your clients apprised of your value, and serves as a useful benchmarking tool, too — no one’s going to be looking to your competitors when they see how much they’re already getting from you.

So when you hit those goals, and especially when you blow them out of the water, make it known. Pick up the phone, send an email, send a gift — anything that will say “we did it!” and communicate clear and undeniable value to your client.

3. Be available.

It should never be difficult for your clients to get in touch with you. While you don’t need to have a pager and be on 24/7 call, you should make client communications a high priority. Make sure that you respond to all messages on the same or next business day (depending on when the message was received).

And have a method in place for continually displaying progress, such as a spreadsheet or organizational platform that both you and your client can access. That way, your clients will be able to get some of their questions answered without ever even having to reach out, which will save them a lot of time and effort.

4. Offer plenty of opportunities for feedback.

Regularly checking in with your clients regarding how they feel about your services will help solidify your relationship. It will also allow you to identify areas where you should be improving if you want to increase your chances of retaining their business. Check-in meetings are helpful, as are feedback surveys during and after campaigns.

If your customer does have a complaint, don’t look at it as a failure. It’s always better to know

about an issue, since it gives you a concrete opportunity to fix it. Nobody is expecting you to be perfect. Instead, your customers want to see that you actively address criticism by owning your mistakes and offering solutions. Giving them a platform to air that criticism if it exists shows that you care.

5. Show your gratitude.

Never underestimate the power of a genuine “thank you for your business.” Clients like to feel appreciated. Even more so, they like to know that you value your relationship with them and take it seriously. You don’t have to go over the top with it, but making sure to occasionally show your gratitude in small ways, or to make a big gesture like a handwritten letter or a deal for future services after an initial campaign has ended, goes a long way.

Here’s the deal: if you’re doing great work and offering your clients respect and transparency, you shouldn’t have any trouble growing your agency retainer business. Focus on doing your best — both in the marketing services that you provide and the way you engage — and your clients won’t have any reason to seek assistance elsewhere.