Using them in each scene will push your story forward and create more tension. Here are some examples of hooks and hangers. These are from my story Call of the Dragon and these first are from the opening chapter.
The King died in his sleep, most unexpectedly.
And the end to that scene is:
The mages were always full of trickery and deceit, but murder! That was going too far.
By the way, the murder at the end wasn't referring to the King (at this point).
You can use these sentences to build tension, drama and take breathers in your story. In chapter 3 I open with dialogue, but notice the urgency in the voices.
“Again! Elias, you must concentrate!”
Elias struck another blow. “I’m trying!”However you choose to use it, your beginning sentences will set the tone for your story. Spend the extra time and work wither your sentences; hook and hangers. They will be the first thing that your reader gets a tatse of and they will make the decision whether to continue from that small bit. You ending sentences will cause your reader to either put the book down for later, or continue reading until the end. And that last sentence is what your reader is left with. Did it satisfy them?
I'm not going to post my last sentence here, it would be giving away the ending of my book. But do you have some good beginnings and endings? Are your scenes good hooks also? Is there plenty of tension in the beginnings? Do the endings leave the readers ready to turn the page?