One of the things I do when writing emails (particularly important ones, or ones going to clients) is after I finish what I would normally write, go back through the whole email and remove as many words as possible.

Things like 'we need to move forward and complete x' become 'we need to complete x'. (sloppy example)

It's amazing how professional the emails look once you remove all the fluff, but it's something so many people dont do.