I’m a big science fiction reader. Mostly I:

• Look up lists of winners and nominees for the big awards (Hugo, Nebula, Arthur C Clarke)
• Read reviews for successive books in a series when I liked the earlier ones
• Find articles on the top SF books of all time or by year, written by respectable sources
• Get recommendations from friends who also read SF
• Occasionally post threads in the SF community here on things I’ve read and see what comes up in the comments