By phone, email or letter
The TLW sends out regular alerts to members asking them to take action on particular legislation. Make your voice heard.
Be brief. Legislators and their staffs are incredibly busy and so are you. They appreciate it when you get to the point and respect their time.
Be courteous. Always, always be courteous. A "How are you?" after the initial hello works wonders! On the other hand, being abrasive is almost always counterproductive, and it provides a good excuse to ignore your request.
Ask for a commitment. The point of contacting your legislator is to garner support for a bill or get their commitment to opposing a bill. After educating them on what what the bill does, ask them if they have taken a position on the bill. If they will not commit, then just encourage them to consider it.