Heroine jumps on horse with no assistance, despite her petite stature and the gigantic size of the equine: take a shot.
Heroine's hair is described as "flowing" while riding: take a shot.
Heroine's hair is called "tresses" or "locks": take two shots.
Heroine's clothing (preferably an impractical, flimsy dress) is described in exhaustive detail: take a shot.
Heroine's clothing is called "feminine yet practical": take two shots (courtesy of
).
Heroine causes every man in sight to fall in love with her: take a shot.
Heroine causes Elrond/Denethor to decide to end his widowed status: take two shots.
Heroine becomes pregnant, decides to go back to her real life and raise the offspring of ..... without letting the child's father know of her condition: take a shot.
Heroine falls in love with Arwen, causing her to leave Aragorn so they can be together (alternative: Éowyn leaves Faramir for her): drink whatever beverage you want in any quantity you like, there's little danger - I've never seen it happen in any fan fiction I've ever read!
No shots are allowed for misspellings, homophones, and grammatical mistakes - no reader can possibly drink that much! 
More:
Heroine is, unknown to herself at first, the heir to a kingdom in Middle-earth: take a shot.
Heroine's singing softens the hardest heart, even awaking the dead: take a shot.
Heroine's name has at least four syllables, of dubiously Elven origin: take a shot.
Heroine's name has at least six syllables, including elements from the various cultures of her mixed genetic background: take two shots.
__________________
'Mercy!' cried Gandalf. 'If the giving of information is to be the cure of your inquisitiveness, I shall spend all the rest of my days in answering you. What more do you want to know?' 'The whole history of Middle-earth..
.'