I think these salutations would depend on how you address the one whom you are writing to. addresing someone with their name such as "Dear Miss Greta", your letter should end with "Yours sincrely" - your letter will look more personal in this kind of format. If you just address them with "Dear maddam" for instance, "Yours faithfully" suits better.'
"Best regards" on the other hand is mostly used in writing a friend or a colleague. Other terms would be "Warm regards" or "Kind regards".
be sure to capitalize the first letter of the first word.
:)