Social media marketing is all the rage these days. The barrier to entry is extremely low (no money required–just create a free account!), so it seems like a straightforward win for your company.

Because it’s so easy to get started, few people think through their social media strategy and whether it’s really helping them. Here are three things to know before you start using social media for your business.

1. It’s Hard to Measure
While some highly focused social media campaigns have measureable ROI, the vast majority are investments in relationship building. And when those investments pay off, it will be difficult to draw a line back to social media.

2. It Isn’t Free
While Facebook doesn’t demand any money to create an account, don’t fall into the trap of thinking it doesn’t cost you anything. The time spent maintaining your social media accounts is time that isn’t spent on your other, measurable marketing efforts.

3. It’s About Your Brand
When your competitors’ products are available online with the click of a button, your brand is what differentiates you. If you have a vibrant social media presence where you take the time to interact with your customers, your company will stand out.

At the end of the day, social media is meant to build trust. And while it’s hard to measure, being trusted is the biggest prerequisite to customers buying what you’re selling. So, while social media may not be for all businesses, many companies have found success in putting these tools in their marketing mix.