A democracy such as the United States thrives on an involved citizenry, and government is most responsive to citizen needs when they weigh in on laws. A proposed law that has not yet passed is called a bill. Citizens can propose a bill to their local, state and federal representatives, and then get involved to help it become law. In order to pitch a law to your government representatives, you need to be informed about current law and ensure that it does not conflict with any other laws.
TL;DR (Too Long; Didn't Read)
Only government representatives can actually propose a bill, but concerned citizens can write to their representatives and work with them to get a bill submitted and ultimately passed.
Know Your Governments
Determine whether your law will apply at the local, state or federal level. Local ordinances are typically the easiest to pass, while federal laws are the most complex and challenging. Laws that affect your life will likely be at the local or state level, so begin close to home when campaigning for a new law.
Draft Your Proposal
Write your proposed law. A bill is more likely to become a law when it is simple and proposes only a minor change or addition to current law, so keep it as uncomplicated as possible. Include an introduction or preface that provides a justification for the law. This justification should include relevant research. For example, if you are proposing a law to raise the percentage of income people must pay in child support, show why this would benefit families. Research showing that current child support amounts are insufficient to support children would help make your case.
Connect With Your Representative
Determine who your government representatives are. If you are proposing a law in a local municipality such as a city or county, you will have a city council or county commission representative. In large cities, this will go by district. If you're proposing a state law, contact the representative and senator who represent your jurisdiction in your state legislature. Contact U.S. congressional representatives for federal laws. Every state has two senators in the U.S. Congress, and each congressional jurisdiction has one state representative.
Pitch Your Idea
Pitch the bill to your representatives. Be friendly, succinct and respectful, even if the government official does not like your bill. The goal here is to find a sponsor for the bill. This is a person who will introduce it to the voting members of a council, commission or Congress. If your representative will not sponsor the bill, start contacting other representatives. While it's best to have your representative sponsor the bill, any elected official can introduce it.