Signature campaign is the reason why we are earning bitcoin here in this forum, we are wearing their signatures and we are going to promote it by posting in the thread where we could post it, because there are some threads that they are prohibiting us to post. You could also read this thread for more information.
https://bitcointalksearch.org/topic/signature-campaign-guidelines-read-this-before-starting-or-joining-a-campaign-1684035
And you might want to ranked up first your account, because the higher the rank, the higher the salary we could get every week, or every month, depends on the campaign.
Yes, signature campaign is one of the best way to earn bitcoins so far. You can earn much money than faucets. Actually there are many ways to earn bitcoins, but i recommend signature campaign and social media campaign. AicecreaME already explain about signcamp and now i explain about social media campaign. If you have twitter and facebook that have many followers/friends you can use it to earn bitcoins. Go to service section and find a twitter/facebook campaign and there is a step how to join and the rates too.
And this Facebook and twitter bounties are most usually in the Altcoin Campaigns and sometimes, we could earn even more bitcoin here than we could earn in a Bitcoin Signature Campaign like in Edgeless, those who participated on their campaign could get 2-3 bitcoin, I don't know the exact amount but it is really big, though this just happens when their ICO is successful and they've collected many bitcoin and tokens.
Altcoin campaigns seems to be risky as you never know what will be the price of altcoin once its listed on exchange sites and many of those coins are scam coins in which only devs will make profits so in that case you will feel that you have been cheated and didn't get paid for the hard work you did for them.
Sigature campaign is one of top earning in Bitcoin but in many ways people have different strategy others is good in gambling and trading while others in signature campaign like me .
and the good thing if you have social media accounts they useful in campaign just check it out in services and find social media campaign
A person who is looking for safe income will always prefer signature campaign as it will give him fixed income and even he don't have to invest any capital into it and people who are risk takers will prefer to go for trading and gambling.