When you are working on a document, don't leave the email open. Deal with work one thing at a time. Distraction is painful. You take twice or more time to go back to what you were working on.
Read your email aloud or in your mind before sending. There will almost be always silly mistakes. You want to look professional.
Keep emails short. Try to rewrite them so that you can your points delivered the shortest possible way.
If you bcc someone, do it because you don't want to get that people flooded with replies. But always tell the rest of the group who is bcc-ed. You don't want the embarrassment when the person in bcc replies.
I find that changing the title to focus on the new key points is important. Helps you find the content you need quickly.