Upgrade your storage with a new hard drive.
Insert an opening pick as far as possible into the seam between the plastic front and the metal rear panel, on the right edge of the iPod.
Use the opening pick to pry up against the plastic front panel and release five retaining tabs (seen in the third photo).
Slide the pick along the edge of the iPod and continue prying to release the rest of the retaining tabs.
After all five tabs along the right side are free, the case should easily open.
Open the case like a book with the dock connector edge at the top, and lay the rear panel next to the front half of the iPod.
Use a plastic tool or your fingernails to carefully disconnect the orange headphone jack cable. Be sure to pull straight up on the connector, not the cable itself.
Grasp the hard drive with one hand and carefully disconnect the orange ribbon cable from the hard drive using your other hand.