Earning bitcoins can be done on all kind of methods but I think one of the best is signature campaigns due to the fact its easy and profitable.
You got almost no risks and its safe to do all the time.
Signature campaign is just one of the ways to earn bitcoin but it is not the best way because you can only earn a limited amount of money, maybe if you are a student living in a country which has a low cost for the expenses then you will be happy with that but if you have big demands in life you should upgrade your method of earning.
Yeah, signature campaign is really good for earning bitcoin but it's limited because many campaign have maximum limit. Actually you can combined with do another service and join easy an free giveaway.