Have you visited a Facebook page that’s filled with corporate messages about why you need to buy their product or service? When I see those, I leave and never go back.
Once you’ve decided on your target market and are ready to post, it’s okay to have corporate messages mixed in, but typically use the 80/20 split. 80% genuine voice posts, and 20% sales. What I mean by a “genuine” post is something in your own voice that will create engagement with your followers. For example, if you sell snow shovels, post a cartoon in the winter about being buried in snow. This will create engagement and your followers will share that cartoon. Their friends will see the post, and share and comment. Right away your reach (social visibility) is expanded by thousands. After a few posts like that you can announce a sale on snow shovels.
Be creative, be genuine, and write your posts as if you were talking face to face with your customers.