How should I choose the right external hard drive to store my books, songs and movies?

What is the best brand to get and should I buy a separate one for each? One for songs, one for books and one for movies? Which hard drive would give me the best bang for my buck?

I have at least one thousand songs right now, thirty books and ten films and will continue to increase my collection. I have a Macbook Pro and wondering if external hard drives only go with a certain OS or not.

Also, what are the things to avoid to ensure a hard drive’s longevity and what are other ways of effectively preserving songs, books and movies to guarantee they would last a long time? Thanks very much for your help and please feel free to just shower me with your helpful tips! : )