How to set up external hdd securely

I just recently purchased a 2TB drive for the sole purpose of hooking it up to the usb 3.0 port of the AC68R and making it my "cloud".

I plan on storing sensitive documents on this drive and want to understand what would be the best way to go about doing this.

I would prefer to truecrypt the entire drive and then automount and dismount it whenever needed/not needed via a script.

Another idea I have is to zip up whatever I plan on throwing onto the drive and assign the zip an extremely sophisticated password.

Are there any threads that cover this already?

Thanks!