Well the way i do it is by like checking the stanza's and if i find recurring language techniques
but you kind of have to memorise different forms, for example Sonnets or Free verse and things.
However, the most you can say about the form in an unseen poem is if rhyming couplets have occurred, assonance, and things.
A Tip i would say is look at AO2 again, which says "Explain how language, structure and form contribute to the writers interpretations of ideas, themes & settings."
So i would just speak about the length of the lines for example short sentence, repetition and things. That's what it basically means.