Anyone can participate in airdrops. Every airdrop has some tasks to accomplish for the reward, some want you to follow their twitter or facebook, some ask for more complex actions. IMHO, it's worth finding some projects like Gravity Protocol, because you can earn tokens for some meaningful actions there, like testing the system, running the node and so on. Just following twitter is boring.

I suggest youtube, there are lots of channels about crypto. Also there are mane blogs on Steemit about cryptocurrency, and some books on the theme. You can also read the WPs of different projects, they often have useful blog posts on how the technology works.

I've joined several airdrops just to look how the things are done, and I think that most airdrops the way they're held now are not interesting. People join in just to receive some tokens and then sell it, and they don't care about the project. I think that the reward must be for the active users that are doing something for the net, and not just for people who followed or liked some social media pages. It will be more efficient both for people and for the projects.

Btw, about the airdrops i've joined, just for stats. There were 100 projects, about ~$5 for each. After half a year I have tokens for ~$100, and that's from 1/4 of the whole amount of projects. Other 3/4 just keep promising on distributing the tokens. As you can see, that's not very efficient.