Painted Girl: The Spirit Key (The Spirit Key #1)
R.A. Winter

Thus began Sara's journey into an unknown world filled with the ancients.
With Grandfather's time on earth growing to a close, a new Key must be trained and ready to replace him or the veil between the worlds will collapse.
Only Sara doesn't appreciate her chosen path and wants to be just an average girl- someone who doesn't encounter ghosts.
The ancients are displeased and do not like her choices, especially her crush on young Jack RedHorse, and a nefarious plot is made against the living world.
But, everything changes when a ten-thousand-year-old spirit returns to Grandfather's farm to help guide Sara with her new powers- but she doesn't believe in him or the spirits.
With a mind of her own, she'll make her own choices in life.
And choices have consequences, including death.