Signature campaign is the only and safest way at a moment I feel to earn bitcoin, if you want to earn more then you need to make initial investment to buy higher ranked accounts but that is worth to spend on it.
I think using your skills and earning bitcoins can be better then signature campaign, i don't say signaure campaigns aren't good, i really can't say that because my own earning way recently is just signature campaign,
But i really feel that if someone has some skills then he can earn more bitcoins quite easily by just working.
I just wish i had some skills like that and could do what i always like to do.
Do not get disappointed mate, you can always learn new things every day, only thing you need is a dedication and hunger to earn more money and every thing will be fine.