Not all of us are great at drawing. There is an element of practice involved but you can give yourself a leg up by 'borrowing' shapes and drawing concepts that others already use to describe things. Instead of having to dream something up on the spot, build up a library of your favourite icons and frames to draw that represent the topic of elements being discussed. Then practice drawing your palette of shapes so they become second nature.
Here is a really useful list of resources to help learn to visual note take and also borrow some shapes and icon ideas for your own palette.
50+ Awesome Resources to Create Visual Notes, Graphic Recordings & Sketchnotes