I'm not much into ghost stories, but I enjoyed The Revenge of Thelma Hill a lot.
It starts off with a scary first chapter, but eventually we learn the ghost of Thelma Hill isn't evil. She just wants Frannie James to help her. Thelma was murdered years ago by her husband, who buried her in the basement of the house where Frannie and her family now live. The ghost wants her bones buried in a consecrated cemetery so she can go to Heaven and for her murderer to get the punishment he deserves. She's certain Frannie is the only one who can make that happen - but how?
The real scary character in the book isn't the ghost, but her murderer.
The subplots include Frannie trying to find out what happened to her own mother, who had left the family when she was two years old, and dealing with her obnoxious twin brother. Since the family moved to their new town during Summer vacation her brother Jeff is the only kid she knows, but they can't get along and quarrel constantly. And, of course, if Frannie tells anyone she has been seeing a ghost they'll think she has gone crazy.
The author, Margot Finke, has done a wonderful job of writing an exciting, tension-filled story and portraying realistic characters and relationships.