first you write a sentence
joe moran's advice on writing which pretty much coincides with what i already had in mind:
find a sentence you like and look at it for a distressingly long time, until you start to see past its sense into its shape. as with a painting, the trick is not to exhume some buried symbolism or esoteric meaning, but only to make time to look. take the sentence apart and reverse-engineer it, the way that computer programmers do when they dismantle software to see if they can copy it without infringing the rights. turn its shape into a dough-cutter for your own sentences.