[header] How to clean and organize a dvd shelf [title] Remove all of the dvds from the shelf or shelves. [step] Separate them into separate piles as you do so, using genres, directors, favorite actors or whatever system you like. A fairly standard approach would be to separate into kids, family, teens, adult, action, rom-coms, sci-fi, thriller, etc. 
Or, go alphabetical or by color--whatever will help you and other householders find the dvds they enjoy watching. [substeps] Use this opportunity to get rid of dvds that you know you won't ever watch again.