I am intermediate.
I wish I had known some of the basic story structures sooner. I only learned those sorts of things when I took a screenwriting class. We read
The Writer's Journey and
Story both of which were very helpful for all of my writing endeavors. I'm sure there must be some sort of creative writing equivalent. Knowing this basic structure made me feel more comfortable knowing I had all of the basic elements that made a good story. It also gave me a good place to start when trying something new or a variant of the structure.
Also, writing poetry really helped to expand my writing abilities. I don't do a lot of it now, but dabbling in it for a time really helped. Reading different poetry styles also helped.
Reading and studying classic books was also helpful to see different types of stories and a variation on the common structures and techniques of today.
I'll let you know if I think of anything else. Feel free to ask me any questions if you want. I think it is great that you are willing to pass on this skill to others.