I like to to go to goodreads after I've read a book and read the reviews and see what other people thought of it. I don't really look at it for reviews before reading a book. I did make an account there and mark down a bunch of books I'd read and look through some lists of recommended books but I haven't really been keeping up with it.

I use my library's website to keep track of books I've read since once I have the books on loan I can just tick a box next to the them saying I've finished reading it.