Its a good question. I have my own tips for success ICO, project should be simple for understanding, team and advisors must have KYC, milestones should be done at time, by the way bounty and airdrops means not so much for me.
Most project team that integrate airdrop into their marketing, know very well that it benefits them more than the community of airdroppers, because first, the project needs community of holders. Also, there is every tendency for the airdrop participants, at least some of them, to trade on the token.