You should use a valid mailing address, especially if writing politicians. Politicians will only care about responses from valid residents, i.e. voters. If writing companies you can state you will boycott them and have your friends do so also. Use your real name, not your screen name or your pet's name. Be courteous and polite, but be strong and speak with conviction.  Most politicians are familiar with the issues.  Give a highlight and request support of cause.  Refer to detailed material if you wish.