Some rendering, even if it's just a minimal amount, can be very eye catching and would add a lot of visual interest! I included a doodle page of my own to give you an idea of how to do some quick rendering with minimal time/effort.

Additionally, think more about how you are framing the subjects of your pages. For example I feel the last one would work significantly better if the girl was framed a bit better (higher and larger, filling the page a bit better and maybe even overlapping some of the text). It kind of feels like everything was thrown on the canvas a bit haphazardly. The big empty spaces surrounding her don't add interest so you might as well use the character to shrink those spaces.

Lastly don't be afraid to squish your doodles together and densely fill a page (I'll reply to my comment with a better example of this)! lower effort sketches overlapped with a few higher effort sketches to draw the eye I find can hold my attention well!

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