Should I have to apply for signature campaign or I have to acquire more knowledge by improving my posts and rank as well.
There are some projects/ICOs that are accepting jr members.
What are the responsibilities/tasks that have to be done after joining signature campaign
Yes a Jr. member may join a signature campaign, but there are also a few campaigns that even newbie can join. It has a campaign of 10-15 posts per week atleast 70 characters upwards and its content should be meaningful, when a project is successful you will be paid. Be careful and research about things in bitcoin when you avoid any mistakes.