Sarah wakes up at precisely 6:43 AM. She proceeds to hit the snooze button until 7:03, when she rolls over and beings scrolling through a news app on her iPhone 6.

By 7:15 she's in the shower singing that Adele song she can't seem to get out of her head.

At some point between 7:15 AM and the end of the day, she buys your product.

Whether Sarah sang Adele or Taylor Swift in the shower that morning probably didn't have any bearing on her decision to make a purchase from you that day.

So what did?

In the B2B space, where you have multiple stakeholders involved in purchasing decisions, the answer to that question becomes even more complicated—and even more important to figure out.

Knowing what motivates your customers' purchasing decisions is essential for building a successful inbound marketing campaign. Marketing to the wrong person could mean your content isn't getting in front of the eyes of the people who might actually buy what you're selling.

How do you figure out what motivates your potential customers to purchase? By creating buyer personas.

Buyer personas can be a huge boon to your business—as long as you know what information to collect and how to use it. Here are just a few ways buyer personas can help with your B2B marketing efforts:

• Better target and promote your content
• Speak the "language" of your most likely customers in your marketing materials
• Gain better-quality leads
• Tailor sales pitches
• Inform product development

Whether you're a beginner who's just starting to explore your marketing options, or a seasoned marketing veteran looking to revisit your strategy, buyer personas are a great place to start.

If you want to start fleshing out your buyer personas, don't get bogged down in unnecessary details (like their shower-song preferences). Instead, start by focusing on demographic data and major motivators.

A lot of that information is likely already at your disposal, and this handy guide will show you how to access it.

1. Start with the basics

Who is actually in charge of making the purchasing decisions in your industry? If you think you already know the answer, give it another thought. Because answering that question incorrectly will render the rest of this exercise, and your inbound marketing, pointless.

In B2B, there are most likely multiple people involved in making the decision to buy your product or service. The CEO might be the one pulling out his credit card, but he is probably not the one who did the initial research.

Nearly half off all B2B researchers are millennials, and they are not in C-suite level positions, according to a 2015 Google study. In fact, 81% of non-C-suite-level employees have some say in purchase decisions.

If you are marketing only to senior-level executives in your industry, you are not going to be very effective. You need to create a strategy to target everyone with a say in the purchasing process.

Accordingly, you will need to create separate buyer personas for each category of person involved in purchasing decisions in your industry. From CEOs to engineers, researchers, and anyone else involved in the buying process.

But, to complete this exercise, pick one persona and stick with it. Eventually, you will have to repeat with the rest, so it doesn't matter which one you start with. Follow your heart, and let's get started.

2. Interview an actual person

The fastest way to get to know someone is to actually talk to them. Simple enough, but many people do not like, or are genuinely scared of, talking on the phone. Get over that fear and pick up the phone.

Once you've chosen which persona you want to focus on, it should be easy enough to find a real life example of that persona.

The easiest place to start is with your own customers. You can bet that someone who has already purchased from you will have some insights about what went into that choice. If you have a longtime customer you have a good relationship with, consider reaching out to that person rather than a new customer.

Keep in mind that it may be more difficult to find someone involved earlier in the buying process, like a researcher. You may have to ask someone higher up to direct you to someone.

If you are a new company and are just starting out, you will have to get more creative to find an interviewee. Use your network of coworkers and friends in your industry to see whether they might have any leads. You can also search by job title on LinkedIn for people you have a common connection with.

Once you have selected someone to interview, don't just call them out of the blue. Email them ahead of time and ask them to block some time out in their schedule. No one likes unsolicited phone calls, and you don't want the conversation to be rushed.

Though it may be tempting to just email a list of questions and ask the interviewee to email them back, you will benefit much more from getting on the phone. A call will allow them to speak more off the cuff and give you a better sense of their personality.

Before calling, prepare a list of questions to ask. You can find a ton of great interview questions for buyer personas with a simple google search. I like this list from HubSpot, but there are plenty of others.

When talking to your interviewee, start with more broad demographic questions, then move on to asking more abstract questions about their challenges and goals.

The hardest part of an interview is balancing collecting valuable information with not getting distracted by unimportant details (remember Adele vs. Taylor Swift?).

One trick is to listen for keywords and themes that repeatedly come up. Jot those down on a separate sheet of paper.

For example, if interviewees mention how they like to start their day by eating a healthy breakfast while browsing the tops stories on Flipboard to keep up with the latest news in their industry, the important thing is not the healthy breakfast or morning routine. What you should take away is that they like to be informed on happenings in the industry.

3. Use Google Analytics data

Interviews are helpful for determining key themes and motivators, but they can be biased because you are getting only one person's view. Although you could conduct hundreds of interviews and average out the data, it would be too time consuming to be worth it.

If you have Google Analytics setup on your company's website, you already have a treasure trove of demographic information just waiting for you to access. (If you don't have Google Analytics set up, I highly suggest you start right now.)

Google Analytics works best for finding demographic data. To get started, open up the Audience tab. From there select Demographics and then Overview. This view will give you a quick and simple analysis of the average age and gender of your visitors (make sure your date is set as far back as possible, so you are seeing all historic data).

You can also learn general information about your persona's interests from Google Analytics. Below demographics, select Interests and then Overview.

The interests section will show you all the affinity categories you might use to reach your customers. Customers in these categories are in the top of your purchase funnel and they are just beginning the process.