I did something similar. After the demo think that's OK. The contrast between the leg and the background was not as striking as the contrast between the head and the body. It looked a bit off to me looking at my version, probably because there's otherwise missing overall shading in the image --- if I understood that right.

I see you paying a lot of attention to detail here -- which is very good for a finished drawing, but can get in the way of exploring shapes and ideas quickly and efficiently when you're starting out sketching. The tertiary details such as the scales, and bumps -- think superficial details -- can wait until after the more important shapes are defined. Focus on the primary forms first. These are shapes that can be made with cubes, spheres, and cylinders. Keeping things as simple as possible in the beginning, you are free to experiment as many times as you like without feeling invested in any one idea. Your first idea will not typically be your best one, so your goal starting out should be to get a bunch of sketches on the page. After you've explored and experimented, you can pick a design or combine elements from multiple successful designs to flesh out more by incorporating anatomy, refining the simple shapes you created. You have a really interesting idea with the fish jumping into the gators mouth! I'd love to see a few more sketches with simple shapes. See how you can explore that idea further.

I think youre on the right track. ‘Design don’t copy’ is a mantra i like to keep in my head when drawing from reference.