Practice drawing basic shapes, then learn to break your drawing into said basic shapes, and adding detail from there.

Most folks will probably tell you to try “being more confident” with your lines, but you’re in the learning process, you can focus on that later. If you want to get started on that now, then just try drawing basic shapes in as few lines as possible.

Right now it seems like you’re trying to extract an image out of your scribbling. Almost like you’re trying to ‘find’ the art in the “marble slab.”