Amazon Keywords - What you should use?

Amazon keywords have always been a mystery to me. How do you pick the right ones? And what do keywords really DO anyway?

Turns out, keywords really matter. @@Using the right Amazon keywords can get your book listed in categories that you can't normally select.@@ Random categories like Military Romance, or Love-Triangle Romance. 

@@Want a list of the Amazon keywords that will put you in the important ebook categories?@@ Just click on the category(s) that you are aiming for.

NOTE: These are only for the US store. 

Biographies & Memoirs

Literature & Fiction

Business & Money

Mystery, Thriller, & Suspense

Children's eBooks

Religion & Spirituality

Comics & Graphic Novels

Romance

Erotica

Science Fiction & Fantasy

Health, Fitness, & Dieting

Teen & Young Adult

History

Textbooks

LGBT

Travel

For the UK Store, the categories are a bit limited and (to be honest), I'm not sure how to differentiate the UK keywords, unless you just allocate some of your regular keywords to the UK keywords. But regardless, here are the links to the UK Categories and corresponding keywords:

Biography & True Accounts

Romance

Crime, Thriller, & Mystery

Science Fiction & Fantasy

Erotica