I think signature campaign is may be the best way for people who are starting their new journey in bitcoin because it can helps them a lot to earn bitcoin in a fast way . I also suggest to sell service to other members like offering your programming skills or web designing and get paid on btc.
Most signature campaign are not available to newbies so I dont think is as easy as you make it out to be, if you really want to earn bitcoin offering a product or service is the way to go.
you are right that signature campaign are not available for newbie and there is a lot of way to grow up your bitcoin and i prefer the one easiest way is trading , trading is very good and anyone can make a fast profit from trading.