Airdrops is one of the several options how to increase your earning.
 I've read in this forum that it takes up to 3months to have a stable income in airdrops. 
Besides, it only takes a few process to accomplished airdrops. 
Eventhough some are scams, there are still legit airdrops. 
While you do campaign and social bounties, you can do some airdrops as sideline 

Just be careful though, don't provide your private key and password same as your email password.