/lit/ - Literature

I want to write a creation myth in form of a poem, but I can't decide on a form. I don't think I want to write it in true rhyme but merely in rythm.
So far I have tried each verse being three lines of eight syllables each, ended by a single three syllable line but it sounds clunky and I dont have much experience in writing poems. Keeping the lines short and snappy feels just like the most elegant approach, so I have not strayed far from that yet.
I already decided that twelve and seven would be important numbers for religions, but I don't know whether to shape my metre after that.
What are some good inspirations for poetic rythms?

How do you guys know what kind of metre is the appropriate while writing poetry? I cannot figure.