There is not much thing I check before joining or picking best signature campaigns.  First off, I have experienced some rejections and scammed projects and that made me more cautious in choosing campaigns.  Since then, before joining, I am making routine check first for who so ever initiated the bounty.  I am not saying I do not trust new members but at least we have to give more credit to those veterans who where here since it started and know way better than us.  Then researching the Initial Currency Offering project, their backgrounds and status as a company.  We could not really predict which best campaign we could join with but at least we could always review it and rely on our instinct sometime.