Avoid redundant writing
One common mistake in legal writing is excessive length. One of the causes of this is redundant phrasing.
For example:
We will provide a written witness statement.
This sentence is one word too long. There is no need to indicate that a witness statement will be written. What else could it possibly be?
This seems pernickety. In a sense it is, but if every other sentence is a word or two too long, the cumulative effect will be significant.