Anecdotes:
Anecdotes, personal stories that appear to support your position, can
ruin the reader's confidence in you if your experience is not
representative of his or hers. Before using a personal story, make
sure that what you are describing has happened to others. If you can
gather many people who have all shared a common experience that
strengthens your argument, you can use anecdote more effectively.
Ad
hominem (personal) attacks: Another
surefire way to make an astute reader question your credibility is to
attack the other side, whoever that may be. Do not succumb to the
temptation to call names or cast dispersions on your opponent,
whoever that may be. Though there certainly are people in the public
sphere who may be out for their own interest over anyone else's, the
strongest case is made by facts. Doing otherwise opens you up to
retaliatory mud-slinging.
Metaphor:
A strong metaphor, comparing one thing to another (ex: “Instituting
this new tax would be highway robbery”) can create an image in
the reader's mind that will stick with them. This can be both a
positive and a negative – make sure your metaphor sounds
reasonable and is well-stated, or the reader may stumble over it and
have difficulty focusing on what you're trying to say.
Wandering:
Once you have your point and purpose, stick to them. Edit your work
mercilessly to make sure that everything supports the point and
purpose and nothing superfluous or contradictory remains. Also cut
out extra wordage, if necessary. In general, the average person will
appreciate three short words rather than two long ones; this may not
be the case when writing to government officials, who are very used
to formality.