There are many ways to earn money on this bitcointalk forum. The first is popular one, signature campaign. The second is on games and round section, on this section, you can check many thread that give you free bitcoin.
Better than both these if you can do it is either 1.) provide a professional escrow service... the other day it took me over 24 hours to find some for a simple trade. 2) manage a signature campaign yourself will earn more vs being in one.