Start by describing who you want to reach and what you want them to do. A local service business might need phone enquiries, while an online shop needs completed purchases. Those goals lead to different choices about content and advertising.
Make the basics easy to find: what you offer, where you operate and how to contact or buy from you. Then choose a small number of channels you can maintain, rather than opening accounts everywhere at once.
Set a budget and review results against the goal. Visits and likes can be useful clues, but enquiries and sales tell you more about whether the activity is working.
The Australian Government's marketing-plan template provides a structure for recording the audience, channels, costs and review dates.