See how different pages can look... you can do anything with a page, just start and see what happends if you have no idea what to do. If you want help with composition make a grid with thirds out of the surface, place things, lines contrast or center of interest on grid or intersections. You can ad diagonals to the grid to create movement. Empty space is just as nice as filled pages. Dare to leave things out, it can create strenght just as well as darks and masses. It is a kind of mass actually.
You can also plan the rhythm of lecture in the sketchbook so that you go from one page to another without being bored and in a harmonious and dynamic way. I'm not and expert with it myself but I'm conscious about it and working on it.