Excellent video explaining Frame within a frame but also takes you through photography history and beautiful examples.
Take an object or person and try and see how many different ways you can frame them within a frame. Minimum of 4 variations.
If you take an hour you could actually knock out probably 50 different combinations that you could put in your book. Different objects if you are at home or different things you are seeing out in the community. How can you find unique was of framing. You can use actual frames, toilet paper roles, road cones. Anything you can see through that has an opening is fair game. Or use something in the foreground (the are of the image closest to you) as a forced frame. Then find something interesting to frame on the other side. Think of it like a game to find as many combinations as you can. Ready...go.