I think what gets a poem going is an initiating line. Sometimes a first line will occur, and it goes nowhere; but other times - and this, I think, is a sense you develop - I can tell that the line wants to continue. If it does, I can feel a sense of momentum - the poem finds a reason for continuing.
Billy CollinsVade Mecum I want the scissors to be sharp and the table perfectly level when you cut me out of my life and paste me in that book you always carry.
Billy CollinsYou, quote, find your voice, unquote, when you are able to invent this one character who resembles you, obviously, and probably is more like you than anyone else on earth, but is not the equivalent to you.
Billy Collins