Do a border and a scribble – then choose one shade of gray and shade in every other shape, which means: No white/blank area may share a border with any other white area, no shaded area may share a border with any other shaded area. Point to point touching is ok. In the original “Draw Good Now” series by E.J. Gold, the “dreaded Number 11” is this same exercise – a mad scribble to be shaded thusly – and – It could be done 🙂
Here is an sample – and yes, there are “mistakes”
When you look at and do these exercises, you will discover things. I could tell you about them – but it will take away from your eyes learning to see and your own experience personally experienced.