Yes, I'm repeating myself. But don't you. Use brevity to your advantage. People are busy. If you can tell them in two short paragraphs why George W. Bush has won your support or why Bill Bradley is all wet on health care, do it.
People are more likely to read a short letter than a long one.
Third, check your facts. We all make mistakes, and we'll do our best to catch yours. But particularly when a letter is critical of a candidate, an obvious falsehood or distortion is reason enough to spike the letter. Fourth, avoid the cotton-candy language of the campaigns themselves. Far better to use the little space you have to give concrete examples of why his flat-tax proposal would change life as we know it.