What you need to start with is gain some knowledge on the ICOs that are offering Bounties. Once you learn about them you need to determine if that will be a successful ICO or not. You can participate in the bounty campaign by signing up through the Bounty Thread or Announcement thread of that ICO. You will have to choose the type of campaign you will subscribe to, and here you will have multiple choices, some of which are Signature campaign, Facebook or Twitter campaign and others. But to get your tokens you must be able to fulfil the needs of that ICO. Then you will get paid in Tokens ofcourse.