I’m late weighing in on the punctuation/capitalization question, particularly in regard to teen writers. Have you considered that Microsoft Word’s default, which capitalizes the first word after a return, may be the culprit. Sometimes just showing students how to turn off the default will also make them conscious of decisions they make about capitalizing.
I also find that helping student writers to focus on audience is helpful. They face the same challenge sometimes when they try to read and interpret someone else’s poem. I suggest reading a poem as if it is a forwarded email whose justifications are all messed up. (Haven’t we all gotten those messages that we need to clean up to read?) Take someone else’s poem and remove punctuation, capitalization, even line breaks, and have students (or proteges) try to make decisions about where they need punctuation to make sense. Compare their choices to the original finished product.
There are even sources that show poems in progress along with the final published poem. Perhaps by having writers see what others have done (while acknowledging that the decisions are personal and individual) you can at least show them that even the small decisions matter in shaping a poem.