The only social media tool I advocate for one hundred percent is blogging. Which, of course, isn’t really a social media platform at all. Which is probably why it's so useful. It allows you to target your audience and craft a detailed message and a precise brand over time. So even if you only post monthly, write a blog.
But what about the rest? What follows is just my opinion and anyone who tells you they know the right answer is just a dingbat. And take everything I write with a grain of salt because I’m not a social media type of person. On a personal level I shy away from these services, engaging with them as little as possible even as I use them as a professional.
For business purposes, I am not a fan of Facebook. Yes, Facebook is by far the most popular social media platform; according to the PEW Research Center, nearly 70% of Americans have a Facebook page with higher earners being more likely to participate. Yes, Facebook is second only to Google in advertising buys. But it’s really social, and that's a problem for businesses. It’s for your friends, and it’s a clumsy tool for getting out a brand or message. You may have "Liked" a business of Facebook, but do you really visit their page on a weekly or even monthly basis? I visit my favorite blogs daily. That's engagement. Facebook will also filter out posts that are targeted to potential clients; unless you pay for a boosted post, they’ll never see them. Because you don’t have a relationship with them. To me, this is a bad communication model, dependent on paid advertising which is exactly the opposite of what people engage on Facebook to see. Facebook is a good tool for events. This is because you're reaching out to your friends and distant friends and really not a friend but somehow you got connected friends. My theatre production company has a page and we use it for every production, posting rehearsal notes, images, and events. Hurricane Images Inc. has a page and I completely ignore it.
Instagram is the next most popular medium, trailing at roughly 30% of Americans. I like Instagram for its quick engagement and because it is a visual medium. It’s one of the tools I use, though I don’t dedicate much time to it. That’s because you can’t really control who you’re talking to, and you can’t provide a whole lot of information about yourself or your service. You can generate a feel about your company, but you can’t direct it to you customers or be specific about who you are. If you use it, have fun, and curate your posts/images ruthlessly to make sure they are your finest. As with many things, there are a rare number of individuals who have managed to parlay Instagram activity into business success, but unless you love using Instagram it's a poor investment.
Twitter. Twitter's numbers are surprisingly low given its status as a social media tool. Roughly 20% of Americans use it, with the highest engagement being among 18-29 year olds. Which may or may not be your client. Twitter should be a better tool than it is (and perhaps I'll figure out how to use it more effectively). It allows you to post images, link to video, and deliver a pithy message. The problem is that you can't control your geographic target, and most production companies end up tweeting about things that only interest other production companies... not their clients. Twitter distills one of the essential problems of social media as a marketing tool: you end up posting about your activities and your interests. Your reader is "you."
LinkedIn is not one of the social media platforms people talk about when discussing social media marketing, but you absolutely should be engaged here. Twenty-five percent of adults use LinkedIn, making it a rival of Instagram in terms of reach, and they use it specifically for businesses. The challenge is figuring out how to be social on LinkedIn. It takes more work. You should participate in groups, be sparing (as in monthly) with your updates, praise and highlight your clients, and write carefully crafted articles and responses. No one wants to hear about you every day, which is its own type of blessing.
My bottom line is this: Blog and use LinkedIn. Look for ways to link the two. Use one other type of social media largely for fun. Don't try to engage on all of the platforms, it's too time-consuming. Pick 2-3 and do it well.