I'm a firm believer in expressing my opions to various legislators. However, I never write letters, I make phone calls. With a letter, some office flunky can read the first paragraph, figure out where the letter is headed and skip the rest or just throw it out. Sometimes important points are never heard.
When you have a living breathing person on the other end of the phone, you've got a captive audience until YOU are ready to hang up. Points can be made, questions answered and feelings expressed better than in a letter.
Also, legislators keep phone logs, so your name and address become part of the record. As well as the subject matter.
As long as you keep your cool and don't start screaming or making threats, your message will get through.