Bounty section provide you a lots of ICO that is still on progress. You should check the ICOs if they had airdrop so you can join. Every airdrop had it's own task to earn free tokens. You can check the links provided in here. I did join some airdrops and i recieved tokens after I completed their task needed. Every airdrop want you to do it's task given to you. I suggest you to join airdrop channels that provide any kinds of ico that had airdrops. An example of telegram group that provide airdrop links are given by payjoe93.