Just consolidating and sharing my knowledge that I have gained so far:

1. make sure that you register for media which send news reg free airdrops like crypto Airdrops and AirdropAlert telegram channels
2. you can follow  airdropalert.com for current and upcoming airdrop
3. Also you can register for PAD Platform - Seems like a new player in Airdrops space.....

Always act fast to grab the free airdrops as they will distribute limited airdrops.
Improve your rank in bitcointalk form, as these airdrop owners give more to higher rank holders.
Sit back and enjoy free salary every weeks

Experts feel free to add more points.....