@JessicaLinnEvans yes -- tonal versions are key! Doing value studies at the sketch stage has greatly helped me improve as an artist.
Another thing that you should seriously think about doing is using a grid template for full page and spread illustrations. There are specific parameters that we can't change and have to work with, especially margins and gutters. In this sketch, you've left sufficient space for text, but it hugs the gutter, which can be difficult to read. Consider nudging the text to the right.
Are you planning on adding more elements to the foreground and background? There are two busy groupings, but there is also an empty swath running through the illustration, and it separates the groups, making them into two scenes instead of one.
Moving a few of these elements around will give you a more balanced illustration, which will also improve the flow and readability. I took a screenshot and did a little visual example of one way this composition could be adjusted.
The text was moved over a smidge. The groupings are spaced out more and the scale was adjusted for some of the animals, as previously suggested by @patricialamas -- to make it feel more natural and to help with the flow. The pink squiggles show where some foreground and background foliage could be added.
Hope this is helpful. So looking forward to you sharing more of your process and seeing the progress with this illustration!
