Categorize the different genres (comedy, drama, film noir, silent) that are important to you, also considering less conventional groups such as "screwball comedies." If your collection is extensive, mull over sub-categories such as "comedies with Steve Martin" or "film noirs with Glenn Ford." Favorite directors, actors, screenwriters or even directors of photography could make up different sections. Remember to have fun. These lists should ultimately make it enjoyable to look through your DVD collection, while easily finding the titles you want.
Scan your list and decide what is most important to you: do "teen mutants-with-tentacles" or "dramedies with one-legged antagonists" resonate more so than "'70s Woody Allen" or the conventional "contemporary classics?" You decide, but remember that all your titles need to be logged, so you may start with "'20s Keaton comedies," then "classic Hitchcock," move on to "John Wayne westerns" and finally "Spielberg/Lucas blockbusters." You might finally choose only three sub-headings, or merely log your entire collection by year, or alphabetically.
Place each DVD into the correct category. Depending on the size of your DVD library, consider an adequate area to work in, such as a large desk or ample floor space. Write each category on a piece of paper, separating and placing them in order in your work area. One by one, place each DVD in the corresponding section. Consider possible sub-sections ("Dirty Harry" as a sub-section of "'70s films") and make all necessary adjustments.
Make sure every film is in the right category, finally placing all films back where you found them: with silent films, '30s/'40s, musicals, Marx Brothers, etc.