1. Read it aloud to yourself because that's the only way to be sure the rhythms of the sentences are OK (prose rhythms are too complex and subtle to be thought out – they can be got right only by ear).
2. Cut (perhaps that should be CUT): only by having no inessential words can every essential word be made to count.
3. You don't always have to go so far as to murder your darlings – those turns of phrase or images of which you felt extra proud when they appeared on the page – but go back and look at them with a very beady eye. Almost always it turns out that they'd be better dead. (Not every little twinge of satisfaction is suspect – it's the ones which amount to a sort of smug glee you must watch out for.)