1. Redeem with Tremor Coins
Register a Tremor Games account: http://www.tremorgames.com/?ref=325470.
Start earning Tremor Coins and redeem your game (you can also redeem BitCoins).

2. Redeem with AppBounty
Open http://abo.io/kewhaiy on your iOS devices.
Start trying free apps and get points.
Redeem your game.

3. Check out Totally Free Minecraft
http://totallyfreeminecraft.com/

4. Get one by sharing a link on social networks
Checkout http://linkbitty.com/FreeMinecraft
You might also want to follow https://www.facebook.com/FreeMinecraftPremiumAccount