They say: revise, edit, revise, edit, revise edit, revise edit, but it's easier said than done.
I'm trying to write a 500 word piece of fiction for an OU tutorial and I'm way over the limit. First draft was 747. Whoops! So I edited and only got down to 653. Damn it! So I've edited again and I'm currently at 572. Better. I'm getting there.
I've had cut out some parts that I really didn't want to, but they weren't necessary for the plot or characterisation. The piece looks much tidier now. I think I need to leave it for a while and come back later to see what else can be tightened, what adverbs and adjectives I can get rid of. Probably most of them.
Writing to a strict limit isn't something I do often, but it's a helpful discipline. Self-editing is painful but enormously rewarding.