Sit down.  Write the whole damn thing.  Look at it.  Sit back in your chair and read it from there.  Get up and pace.  Sit down and read it again.  Think: Shit, this is brilliant!  Print it up.  Go get some coffee/beer/wine.  Tell everybody you’ve written your best poem yet.  Go get it from your desk and read it.  Realize it’s actually the most god-awful pretentious crap ever committed to paper.  Crumple it up and throw it away.  Erase the file.  Sit and feel humiliated and stupid.  Decide that no one has ever written a really good poem about feeling humiliated and stupid.  Write a stupid couplet about what a schlumph you are.  Realize nothing rhymes with schlumph.  Go get some more coffee/beer/wine.  Get mad at your stupid self for being such a sissy.  Start another poem.  Have absolutely no inspiration whatsoever.  Decide, what the hell, Hemingway couldn’t write worth a damn, and look how far he got.  Start writing one-syllable words.  Remember a couple of lines from that sorry excuse of an ink-waster that you wrote earlier that actually weren’t so bad and look for the file.  Remember you erased it.  Curse loudly, alarming your spouse and spilling the dregs of your coffee/beer/wine.  Go reassure your spouse by lying that you had just stubbed your toe.  Go back and clean up the mess, discovering the crumpled paper with the poem containing the not-so-bad couple of lines.  Start reading it and realize that, actually, with a little work, it could be a pretty good poem after all.  Go to bed about midnight, feeling tired but great.