I use Goodreads to keep track of the books I have read/want to read. I love that site. Before that I was trying to use Amazon and add books I wanted to read to a wishlist, but that was a pain to use.
When I started using Goodreads, I wasn’t sure how I wanted to rate books. I didn’t have a method. I seem to have developed one, and it goes like this:
☼: I couldn’t finish it (due to poor writing quality, poor character quality, the story having one or more elements which annoyed/bothered me, being dead boring, all of the above, etc).
☼☼: I managed to finish it, but only through the application of a considerable amount of willpower. Or, I finished it, but I wished that I hadn’t bothered.
☼☼☼: Was ok. If this is the first book I’ve read by a particular author, I’m probably not going to read any others unless someone is very, very convincing. If this is not the first book I’ve read by that author, then I might continue reading if the others were sufficiently good.
☼☼☼☼: Was good. Enjoyed the book, and will be reading more by that author.
☼☼☼☼☼: Was awesome. Will reread. Either own it or will own it very soon.
There. That was surprisingly simple.