Hi @KathrynAdebayo . Thank you for sharing your art. For me personally, I love your graphite rendering..the first image..considering you aim for children's books illustrations. You could also scan them & print them out for glazing with transparent mediums if color is required.
I understand where you are coming from..I work in a few styles as well. I attempt rendering realism digitally, I have a line-art style with vibrant colors & traditionally I work with inks, watercolours & acrylics as well. I think the key is to do more works in a certain style for consistency & confidence :). Also, do you have a preference of a medium that you tend to enjoy more than the other mediums? I find that it's quite important to enjoy what you do as it shows up in the work.
I suggest to keep working in a style that you feel the most confident in and produce more art in that style & work on the other styles/ mediums through experimentation with a rough timeline or schedule in mind. Another thing to consider would be how long a certain medium or style takes you to complete an illustration considering the business of children's book illustrations. The faster you work the more projects you can take up..if that's what you would like to do.