I am a real estate marketing specialist and have seen many agents I work with posting successfully to Facebook, LinkedIn and Twitter. Appearing on Google searches is great and important, but it's crucial to be marketing where your target market’s attention already is. You don't just want to wait for people to search for properties with keywords that match your descriptions, it's even better that those properties appear in front of them on social media before they actively start searching for a new home.
If they search on pages like Zillow there's also a big chance another agent who paid a lot of money for the Zip Code privileges is going to get their business instead of it going to you. Also you should pay attention to several property portals, not only Zillow to be sure to not miss out on opportunities. Short-term sales tactics like paying Zillow or Trulia for leads is the same as paying a referral fee for a lead. Zillow owns their attention. To be a successful agent, you need to combine short-term sales tactics and long-term marketing strategies.
Long-term marketing strategies require building a personal brand so people recognize you. If you use social media to post consistently, you can own their attention.
How do you do that? Share personal content so they know you, professional content so they trust you, and business content so they deal with you.
The only way you can compete with Zillow and avoid paying the referral fee is if your connections think of you before thinking of Zillow. That's why you need to post consistently on social media to stay top-of-mind.
If this sounds like a lot of work, it is, but there are many tools out there to help you with content creation apart from posts about your properties to reach and maintain interest form people who aren't interested in changing their living situation right now.