This step you can do while installing Linux also, but it will be very complex while installing Operating Systems like Arch Linux. Jefro is right the sure way is with Pendrive. To me this has happened several times and I'm always in this case I use a program called GParted to format the USB drive and hard drives. How to correctly format the USB stick in Linux Mint.
With hybrid images, you can simply write the content of the ISO and make a bootable USB stick which can install Linux Mint by using the 'dd' command. How do I install linux mint on an external hard drive. Now take a deep breath because its time to go for Linux installation section. How do I put Linux Mint on a USB stick.