Stick to two clear fonts as a maximum. They have to be appropriate to the style and genre of the digipak and advertisement.
Stick to three colours as a maximum and make sure the are appropriate to the style and genre of ancillary work. (digipak and advertisement)
Use clear photos that are in focus. Make sure they are the appropriate size of each panel and genrically appropriate.
Follow the rule of thirds.
Include the barcode, date, copyright information, title of the album, artist name, record company logo, website and artist website.