Earning money is never free. The best way to earn bitcoin is to do whatever you do best, whatever pays you the most per hour/day/week. Do that...and either ask to get paid in bitcoin or use the fiat you make to buy bitcoin.
It's that simple...and difficult.
What do you do best? Maybe we know some folks that need that kind of work.
This makes the most sense.
The original question was "how to earn
faster" but airdrops or signature campaigns take time until the coins earned are worth something.