Signature bounty is one of the best ways, together with twitter, telegram and facebook bounty. I usually judge a project by the number of members of its social platform.
I think one of the best way in order to promote such an ICO is to join with their bounty campaign, facebook campaign, twitter campaign and telegram. By joining in this campaigns you will be able to promote their ICO at the same time you will earn also tokens that can convert into money so that it is a win win situation.