I don't do social bounties because I don't like to spam my friends / contacts with random projects that may not be of their interest. I don't want to have my twitter or facebook personal accounts flooded by tweets, retweets or shares, honestly. But many people do. You could do all social bounties offered by the ICO, or select which one is better depending on what they are paying and the % of stakes each one has.

I only do bounties for projects I will invest in, and I really care about. For me is a way to get some extra tokens for free, that will have value long term (or at least I expect to, because I am putting my own money into that project).