Essentials:
USB Port on your PC/Laptop
USB DATA cable (the one that came with your device)
Enable OEM Unlock - Goto Settings > Additional settings > Developer options > Enable OEM Unlock
Enable USB Debugging - Goto Settings > Additional settings > Developer options > USB Debugging - Enable (If you have not activated Developer options, then Goto Settings > About phone > tap MIUI version 7 times > You are now a developer)