I had remembered Help's title out of the blue the other day and ordered it and Goodbye off Half. I also got another book that I remember reading over and over -- Poison! Said the Cat. It's actually part of a trilogy, so I bought the other two books also: Blood! and Thief! They're about a girl named Kiki who works for the school newspaper and has a big orange tabby cat named Pumpkin, and they solve crimes. *grins at the cheesiness of it* I think I was reading these during the days of The Babysitter's Club and Sweet Valley Twins.
ETA: Ooh. I also remember the Castle in the Attic books by Elizabeth Winthrop (the fact that that book hasn't been movie-fied yet just amazes me) and The Seventh Princess by Nick Sullivan (I loved that one so much I even tried writing a sequel for it! My first fanfic. There was ship, too.) I guess I was kind of on a fantasy kick even back then. Then I started getting into horror... RL Stine and Christopher Pike (Pike was preferable because the scary things in his books were all really supernatural -- aliens and monsters and witches and the like -- whereas Stine's were always explained away rationally. Even then I recognized it as a more sophisticated version of Scooby-Doo.
There's this one horror book and I've been trying to remember the title for years -- I think I even asked for help on this journal once but to no avail. I just remember that there was a girl and she bought an old mirror at a swap meet or something, and it had all these moons and other designs carved into the wood. And when the full moonlight (I think) is shining on it, she can see into the house where the mirror used to stand in the past. And there's a girl there and one night the girl reaches through the mirror and pulls the main character through, and she's trapped in the past and has to find a way to use the mirror to escape. *sigh* I even remember that the cover art showed the pulling-through scene, but I don't remember anything about the title.