Fans unlike/hide pages who post too often. Facebook also starts to treat these pages as 'spammy' and doesn't show these posts to as many fans.
While it is a good idea to post daily, try not to post more than 3 posts a day. 1-2 posts are ideal.
Also, since posts continue to appear for a few hours, try and keep around 3 hours between posts if possible.
To make this easier, you can use the post scheduler:
- Type in your post in the 'Status update' box.
- Click on the little ‘clock’ icon immediately below the text. It's the one on the extreme left.
- You can now choose what time you would like your post to appear.
IMPORTANT:
Make sure you are using Facebook as your business and not as you personal profile, else this option won't show.