Constituents always receive attention. State exactly what you want your Representative or Senator to do. Don't be vague. Request a specific action on legislation. Personal insults, threats, or yelling will be discounted.
Nothing is gained by being argumentative.
Steer clear of heavy doses of philosophy - you're not going to make a politician change his or her life beliefs in one phone call. Make your reason clear and precise by emphasizing the practical benefits or dangers of the legislation. Don't deluge them with facts but have one or two good nuggets of information you can mention to bolster your arguments. Don't be bashful or intimidated. Your Senators, Representatives, and their staffs are there to serve you.