Tips for working on bigger pieces, try not use too much pressure. It must just be heavy enough to show you clearly on the reverse side where to press out your design, but not so heavy that the background competes with the foreground. Take your time.
If you are going to design something for a cover of a book make your design work with the shape of your journal. In this case the book is A4 but landscape, so the information is easy to read in this half moon design.