Carly's Ghost by Peggy Tibbetts is suitable for younger adult readers (as well as older). Based partly on the author's own experiences, the story is much more charming than scary.
Carly and her family move to a cabin and soon strange things begin to happen. Doors slam unexpectedly and Carly's bullying older sister keeps having small accidents that she blames on Carly.
Carly does her own investigating and soon discovers a secret room, an old diary and a much loved but battered doll. In the end, she finds a friend in the ghost.
The nice thing about this book, especially for younger readers, is Carly's character. Anyone with a sibling has lived through the same problems Carly has. And Carly's tenacity and strength make her a very likable girl.