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.
You are right, but if you are not ready to join the signature campaign and need to know more, you may first learn to avoid mistakes.