No matter what platform you are using to present your case, it's always been rule #1 to keep your audience in mind. A social media strategy is no different, and perhaps even more complex because there are almost two separate audiences to keep in mind.
The first audience comes from who's already tuned in. You can very easily check your analytics to get a good perspective on the age, gender, and geographical area that is subscribed to your feeds. It's good to know who is already listening and helps define who is currently interested in to what you have to say. This group will likely be your loyal crowd and should not be forgotten, but there's also the group that you would like to have listening, that you need to pay attention to.
Let's say you are a restaurant, with a great social media following of 30-40 something women. Chances are they are following you on Instagram and Facebook as that age group tends to flock there. When you glance around your restaurant you notice a good amount of 20 somethings, maybe younger, (t's hard to tell these days sitting at 40). Where are they and why aren't they listening to you on social media?
Different age groups consume social media in much different ways. GIFS, videos, and quick quirky meme's grab the attention of a younger crowd. If you're seeking a broader audience, go to where they are. Perhaps you create a Snapchat of behind the scenes kitchen stories, attracting the attention of that younger crowd, while continuing to produce high quality images for your current Instagram account.
When considering audience, and going to where they are it's good to remember to be fluid, but still stay true to your voice. There's no reason to run off course from your goals and authenticity just to reign in some new listeners.
You may also want to sketch out that ideal customer when you first set up your business and find where they set up camp on social media. Don't limit yourself in this exercise. If your goal customer feels like a fish too big to reel in, don't let go. You at least need to start out fishing in the right pond or you for sure will never catch that big one.