We all know clichés are bad and that fresh, inventive and "fitting" phrases will delight and entertain our readers.
What techniques can be used to invent such phrases? Sometimes they just "fall out" while you're writing, but other times require intense effort. You could do things like throw random words or direct opposites together and see if that inspires something, but I suspect this has a relatively low return on investment (time wise).
What successful techniques have you used?
(Here's a link to a site with a great colour scheme that talks about types of clichés).
 Unless you want one of your bad guys to spout clichés as a character trait
 Because good guys are never clichéd...