A good caption is hands down most important in terms of copywriting. I ask myself important questions before posting to social media, such as:

What will my audience's reaction be?

What will my audience's reaction be?

What will their reaction be to this information?

Will they find it entertaining, or am I the only one who finds it entertaining? 

I conduct studies about the client's services or products as part of my role. I also create captions for promotional sales, provide responses to client inquiries, and encourage them to communicate through comments and replies.