you cannot get free bitcoin. it is not a magic. you need to invest or deposit... i think
i advice that you joined in the airdrop. its free.
Yes you can get free bitcoins. There are lot of legit sites that pays you bitcoin for your service, mostly Paid To Click sites and Faucets are commonly used to get free bitcoins. You can also try dice rolls gambling sites only if you have lots of luck. I started free bitcoins back then from PTC and Faucets so they are really paying before i came to bounty hunting and airdrops. So give a try and see it for yourself and it FREE.