When I say “packaging” I don’t mean the CD case or vinyl sleeve. I’m talking about the collateral for the release. The artwork, the one-sheet, the promo materials, artist photos and any extra things you want to include in your release.
At the very least you will need all the audio tracks – in .wav (or other uncompressed) format, and you will need artwork, in high-resolution image format.
Collect them up and stick them in a folder on your computer somewhere. Keep them safe!