Earning money with the bitcoin can be done on all kind of methods, I think the best method is by doing it by trading in altcoins and campaigns.
Its both not very difficult and easy to understand and its also profitable and that is of course important.
Agreed with you that signature campaign is profitable without taking risk which is most of the users here are participating in signature campaign but in trading that is risky your profit is depend on your luck. Thats why the only safe is joining in campaign if you are not in hurry to earn bitcoin