The site American Passages: A Literary Survey, includes brief background on John Ashbery.  Open up the Author Questions on the page and refer to the questions to spark analytical thinking about the poems.

This video offers a lecture on Ashbery’s Self-Portrait in a Convex Mirror.

You might also enjoy Smarthistory/Khan Academy’s discussion of Parmigianino’s painting, Self-Portrait in a Convex Mirror.

This video discusses the experience of reading Ashbery’s poems.

This video interviews Ashbery and discusses his poetry in general.