Today, we\u2019re going to show you how to create the perfect product to complement your main offer \u2013 a product that excites your customer base and expands your revenue stream.But first, let\u2019s take a little trip down Imagination Lane.Imagine, if you will, a world where burgers don\u2019t come with fries. Insane, right? We think of a burger and fries as an inseparable pair. But it wasn\u2019t always that way.In the days before fast food chains struck it big, most burger joints served up lots of different side dishes. It wasn\u2019t a given that your burger would come with fries. Then McDonalds came on the scene, and took a different approach. They wanted to focus on a single side that was tasty, affordable and portable (these being the glory days of drive-thrus). It also needed to be something special that customers couldn\u2019t make for themselves at home.French fries were the answer.Now, \u201cdo you want fries with that?\u201d is a part of the American lexicon. McDonalds buys 3.4 billion pounds of potatoes a year in the U.S., and they sell 9 billion pounds of fries around the world every day. Anyplace you order a burger these days, you expect that you\u2019ll get \u201cfries with that.\u201dMcDonalds did more than take the french fry mainstream. They created the perfect \u201ccomplementary product\u201d to accompany their core offering \u2013 the hamburger.You probably have a core offering, too. It\u2019s the centerpiece of your business, your primary sales focus. It could be an online course, or an e-book, or a video series \u2013 whatever product you\u2019re best known for.At a certain point, you need to sell something in addition to your core offering.You have to come up with an idea for a complementary product \u2013 your fries, so to speak. And just like McDonalds asks if you want fries with that, once you have another product on your menu, you can sell it to customers who are shopping for your core offering. Not only does this increase your revenue, it provides your customers more value. It\u2019s a win-win.Retail stores are the superstars of this game. Take pet supply stores, for instance. A place like PetSmart or PetCo relies on dog and cat food sales to pay the bills. That\u2019s their core offering, their staple, because the one thing every single pet needs to survive is food. Right?But pet stores don\u2019t stop there. They\u2019re filled with complementary products: Treats, toys, beds, leashes, flea prevention, grooming tools, silly costumes…the list goes on and on. Every time someone stops into the store to stock up on pet food, they leave with a complementary product (or two or three) that they didn\u2019t even know they needed.Why is this approach so effective? Because retailers know exactly who their shoppers are and what they want. Pet stores know that pet owners are devoted, caring and will buy anything to make their pets happier and healthier. So, they stock hundreds of items to help their customers do just that.To develop a high-performing complementary product, you need the same insight into your customers:Who buys your main product?What kind of person are they?What do they want?What can you sell them to fulfill their needs?Here are a few ways to get you started collecting insights about your buyers.1. Create a customer avatarGet inside your customers\u2019 heads by building an avatar. Ask yourself some demographic questions to get going: Is your primary customer a man or a woman? How old are they? Where are they from? What is their lifestyle?Then go a little deeper and add a psychological profile. What is their biggest challenge to overcome right now? What need in their life does your core offering fulfill? Is it a physical, mental, emotional, financial, or educational need? After your core offering has helped them fulfill that need, what other (related) needs remain? How else can you help them or provide value?2. Survey your customersSurveys are an amazing tool to find out what your customers want, right from the source. It\u2019s easy to email all of your existing purchasers with a link to an online survey with a few simple questions.Start off by asking them which topic from your core offering they want to learn more about. You can include a drop-down menu in case they don\u2019t recall the topics. Then, ask a broad strokes question like \u201cwhat\u2019s the biggest challenge in your life right now?\u201d to see what they want help with. End the survey with three potential complementary product descriptions and ask which one they would most likely buy.If you get a low response rate with an email survey, don\u2019t hesitate to hop on the phone. Create a short list of people you think best represent your typical customer and give them a call. Start with the same questions from the email survey, but be prepared to let your customers direct the conversation. The most important thing you can do at this point is listen.3. Stalk your customersNo, not in a creepy way! This is a helpful exercise because methods #1 and #2 above rely on your customers giving you accurate information about themselves. And sometimes, that\u2019s hard for people to do. They might not know what their issues are, or what products they\u2019d be interested in. Sometimes, you can glean the truth about your customers by seeing what they\u2019re up to in their everyday lives.All you have to do is look for them wherever they might be expressing themselves publicly online. Then, you can interact with them, or just observe.For example, if you sell a product about getting ahead in business, see what your customers are talking about on LinkedIn. If your product is focused on lifestyle or health, see what your customers are pinning on Pinterest. Facebook, Twitter, Instagram and YouTube are great places to start no matter what kind of product you sell.Learning about and listening to your customers is the #1 way to ensure you\u2019re creating a kick-ass complementary product that they\u2019ll absolutely love.It\u2019s not enough to just think about it. You have to take action.Now it\u2019s time to sit down and evaluate the information you\u2019ve gathered. What trends do you notice? Are a lot of people mentioning the same things? Are they interested in a particular topic? Pay attention to these trends, and use them to develop some initial ideas for your new product.When you have a product idea you\u2019re crazy about, evaluate its strength by asking yourself these questions:Is my complementary product thematically tied to my main offering?Does it seem like a logical \u201cside dish,\u201d a pairing as good as a burger and fries?Is this something my \u201ccustomer avatar\u201d will be excited to purchase?Does it fulfill a need in my customers?Will I feel confident selling this product to people who have purchased my main offering?Do I believe this product provides value to my customers?If the answer is YES, you\u2019ve hit the jackpot. It\u2019s time to build your complementary product and offer it to your customers. Here are a few ways to start selling it:You can sell it as a bundle together with your main offering \u2013 just like a McDonalds value meal that gives you multiple items.You can sell it as an upsell while the customer is in the process of buying your main offering \u2013 just like asking \u201cdo you want fries with that?\u201d to someone who only ordered a burger.Or, you can sell it as a cross-sell\u00a0when your customer is nearing the end of their experience with your main offering \u2013 just like suggesting someone order a milkshake for dessert when you see them about to finish their burger.You can even sell your new product all by itself, and that can lead your customers toward purchasing your main offering. It\u2019s just like going to the drive-thru because you\u2019re craving some fries…but once you start to place your order, you decide to get a burger, too.What we\u2019re saying is, when you have a complementary product, you have lots of fantastic options that all point to more sales. The important thing is to watch how it performs. Get sales data, request customer feedback, and be prepared to test it and tweak it until it\u2019s as enticing as an order of fries. You\u2019ll be well on your way to increased revenue and happy customers.