Interesting a newbie account asking about signature campaign, you need to be a Jr.member to participate in most signature campaign, I will advice you to focus on building up your account rank before discussing a signature campaigns. Newsletter and likes of social media campaign you can start with
Basically to be of signature campaign participants first must be Jr.member rank. Then choosing a good campaign check the participants,check bounty manager and the project itself. Usually good campaign signature hired veterans participants and good bounty manager.