I am not too sure which "principles of writing" you are referring to, and you might want to post them to help editors like me answer your question. I do believe, however, that I can respond as to how Poe tried to create something new in this excellent poem, and, as the fame of this poem gives testament, succeeded with great aplomb.
In writing "The Raven," Edgar Allen Poe deliberately planned to create a verse form that was original and to invent new effects using alliteration and rhyme. You might want to consider how he does this using internal rhyme, which can be defined as rhyme that occurs within a line of verse or repetition of an end rhyme within a line. Note how "dreary" and "weary" present this phenomenon in the first line of the poem, swiftly supported by three more examples in "napping," "tapping" and "rapping" just a couple of lines further on in the poem. You might also want to consider the way that he creates remarkable rhymes in ways that are completely unexpected. Note how "window lattice" is made to rhyme with "what thereat is" in lines 33 and 34.
Likewise we see ingenious use of alliteration to create an onomatopoeic effect. Note how this operates in line 13:
And the silken, sad, uncertain rustling of each purple curtain...
The repetition of the "s" sound helps create the rustling of the curtain here.
So, it is clear that Poe was trying to achieve something new and distinctive in this poem, and we can see that he was successful in this goal.