1. It's much harder to write less than more. Not everything needs to be flowery, sometimes it's much more effective to use simple, direct language.
2. If you're struggling to write, do something else for half an hour and then try again. Never force it, it doesn't work like that (not so easy when you're on a deadline, but there's always a few minutes for a cup of tea!)
3. A sentence may sound lovely and show off your skills, but if it doesn't fulfil a purpose, cut it. As Sir Arthur Quiller-Couch once said: "Murder your darlings".
4. Only write something you'd want to read yourself. Don't put something out there that you wouldn't find interesting, because chances are no-one else will either.