1. Look for the most recent ICO, whose followers directly booming.
2. Note the type of project, choose a project that you think is different, and can be useful for many people.
And Remember!, any type of project if there is no promotion certainly the project will not succeed, therefore you as a bounty participant do not just work in formality only, you should really think for the promotion of projects that you share in social media work effectively, so you must make surethat every post about the project, the post should really be seen by your people/followers in social media.
choosing the right icos is quite hard to find. i prefer that you will go to ICO Bench. ico bench helps you to find good icos there such a rating experts there better check it out.