Keep live projects on an external drive. The exception to this is if you plan to compress the project into a ZIP file before placing it in on the drive, transfer it from the drive to your computer whenever you want to work on it, and unzip it once you've done so. This is a bit of a pain, so if you're only using the external drive because you're worried about your hard drive crashing (and taking your work with it), you're probably better off storing your backups on the external drive instead.