Signature campaign has always been the most rewarding way to earn a decent amount of Bitcoins. The only you would need to do is to invest your time to make quality posts and you'll be earning good profits. Trading is also a great way to earn Bitcoins, but you need to have experience in doing such task. 
Just keep in mind that you shouldn't think about earning with the signature campaign on. Instead, focus on your posts and contributing to the forum, and you will be rewarded with knowledge, experience, and happiness.