1. Your device needs root!
2. You have to unsign APK (sometimes unsigned APKs are uploaded too, then you can skip this)
3. You must install original game and login with Google+ or FB (don't remove game after!)
4. You have to install the Apps: Lucky Patcher (Look video tutorial)
5. You have to patch the signature verification
6. You install the modded APK over the original game
7. Thats it =)
Link download luckypatcher:
Download Lucky Patcher by ChelpuS