Social media is a staple for any modern marketer.

Among social media platforms, Facebook is the behemoth -- the 800-pound gorilla. Its December 2016 numbers are astonishing: more than a billion daily active users, both generally and on mobile.

Now that Facebook is emphasizing video content, it's essential for every business, no matter the size, to consider using video to reach potential customers. The good news is that these days, it's easier than ever to create a video with the smartphone in your pocket.

Inc. spoke to two viral-video creators about their tips for creating content that users will want to share. Karen X. Cheng is the head of an eponymous marketing agency, whose most recent Facebook video campaign for the book Good Night Stories for Rebel Girls has achieved 24 million views. Cheng's friend Benjamin Von Wong is a photographer who pulls stunts like posing a model underwater with sharks, or on the unprotected edge of a skyscraper. His Facebook page has garnered 268,019 likes, and a video that he posted in December has reached 22.9 million views.

Together, Cheng and Von Wong know a thing or two about making videos go viral. They have very different aesthetics -- Cheng's videos are informal and approachable, like a slightly more polished version of something you'd see on a friend's Snapchat, whereas Von Wong's videos look like scenes from epic fantasy movies. Here's their advice.

1. Copy the approach that's already working.

Cheng and Von Wong both emphasize the need to study the popular content on Facebook. "It's observing what other people are doing and observing what takes off," Cheng says. She gives the example of square-size videos -- it used to be that most videos shared online were landscape-oriented, but then creators figured out that square videos take up more landscape on smartphone screens.

Trends wax and wane based on audience whims and on Facebook's own priorities, so it's important to keep paying attention. "Every change that the Facebook algorithm makes, I am eyeing that and I am ready to change my video strategy," Cheng says. For instance, she points out that Facebook actively suppresses YouTube or Vimeo links. Videos uploaded natively to Facebook will do much better.

2. Book smarts shouldn't be neglected.

Cheng recommends Made to Stick, Chip and Dan Heath's treatise on concepts that burrow into the brain, while Von Wong mentioned Jonah Berger's Contagious. Understanding the psychology of how the human mind processes information, and the role that content performs in our social lives, is key to brainstorming the right idea for a viral video.

And no, the secret isn't cats, As Berger has explained to Knowledge@Wharton: "There are definitely some cat things that become popular, but that really doesn't tell us anything about why most things go viral." For that you need to examine the research.

3. Optimize for people's real watching conditions.

The first frame of the video needs to grab people right away, because otherwise they're going to scroll past without watching. In the past, people would discover a viral video by reading a news headline and then clicking through with the express purpose of watching that video. Now they're browsing through their friends' posts, possibly while standing in line at the grocery store. These Facebook users are likely semi-bored and willing to watch a video, but it has to be eye-catching enough to pique their interest in a split second.

You should also be prepared for your video to be watched without sound -- even when Facebook rolls out audio autoplay completely, users will be able to mute videos with ease, so you can't expect them to be listening. "I typically edit [videos] with sound off [...] on a tiny, tiny screen," Cheng says. "It's the return of the silent video!"

Last, but absolutely not least...

4. Content is actually king.

Von Wong suggests trying to think from the audience's perspective: What is your video going to do for them? Does the video cater to their interests and needs? Cheng says bluntly, "If you don't have a strong shareable concept that's executed well, the video is going to tank." So it's back to step one -- figure out what the Facebook audience wants based on what they're already watching and sharing, then re-purpose the techniques for yourself.