Have a reason for everything you do when you are writing. I don't mean that you have to be paralyzed with self-consciousness, but writing is highly charged with intentionality. You choose one word over another, you choose to change or not a change a sentence to avoid passive voice.
When you are learning to be deliberative, you will agonize over every sentence and move very slowly. Then, certain decisions will become habitual and won't require conscious decisions.