You already know the answer: every creative artist has to keep an open mind about the “rules” of his craft.  Some of the rules for poets that come to mind are these:

Avoid gerunds (-ing words)

Don’t use question marks in poems

Haiku must have seventeen syllables.  (There are in fact two camps on this one.  It depends on which website you go to.)

Poetry is supposed to rhyme.  (This one only comes from the audience these days.)

Nobody uses metaphor any more.  Of course I consider this one a minority opinion, but it was spoken by a teacher of poetry.

All these I consider optional.  There is only one doctrine to which I still cling:

There is always another way to say it