Individual citizens can best influence public policy by
participating in public demonstrations, signing a petition, and voting. signing a petition, participating in violent demonstrations, and voting. assembling in front of a legislator’s home, writing a letter, and voting. talking to the media, calling their representatives, and voting.

Participating in peaceful demonstrations is in any case better than participating in violent demonstrations: peaceful demonstrations are taken more seriously than the non-peaceful ones.
The most effective ways are:

participating in public demonstrations, signing a petition, and voting.

These means allow the people to unite; and if many people show their support for a cause, they will likely be taken seriously.