It depends what your social application is about.You could use social networks (Linkedin or Facebook Marketplace and Groups or SnapChat), networks such as Quota or Slack, Reddit.
Just start with a plan, who is my audience? What content I want to deliver? Which is the right channel to do this even based on your location (e.g. I will use VK in Russia and WeChat in China, flea-markets apps in Japan, probably not Facebook)? Use the right images, these could be more beneficial than a long description. Select the right timing for sharing anything and maybe do that even more times.