There is a lot of ambiguity on how to signup for notifications for page on Facebook that you like. Many people are still not aware of it. Here is a simple guide how to do it :
1: Go to the Like button on the page you want to follow. When you take your mouse cursor on the button a drop down menu will appear like below. Select “Posts in News Feed”.
2: After this a second box will appear and here you can select “Default” or “See First”. It is better to select “See First” so that you don’t miss an update from the page. After this select “done” and you are good to go.