I also think airdrop is a very good way to start without having to invest (just time  ), provided you choose them well it can even pay off quite well.

Then you have to know how to make your earnings grow by replacing them wisely, but this is valid in all cases (a way that can be interesting is to participate in ICO with the money earned with AD).
The risk is greater than betting on currencies that are already listed, but the reward as well (it allows to buy crypto at reduced price with often  bonus).

And since it's free money, if it doesn't work it's not too bad