Depending on your genre, try checking out books by award winners as a means of finding good authors. Then work outward from there. I joined WorldsWithoutEnd.com and found a lot more scifi books that hit a 5. I don't like all scifi, I prefer action/adventure over hard science although Peter Hamilton is an exception. With fantasy, I'm much more selective as I too have hit a lot of books that while popular, don't fit me. Also, as someone said, go to your library. Librarians are great sources for books that are similar to what YOU like. Finally, try the
literature map. I put Terry Brooks (sword/sorcery fantasy) in that and only one author (Elizabeth Moon) comes up that I don't really enjoy (too detailed). Same thing when I put in Michael Connelly (detective) - the surrounding authors are right up my alley with only a couple of exceptions.
I love anthologies and yes, some authors are excellent short story writers and their novels suck and visa versa. But I feel most whom I've enjoyed as a short story writer, I've also enjoyed as a novel writer.
Finally, it helps to try out books recommended or commented on by others here on Mobilereads. Some members here clearly have tastes similar to mine, so I'm happy to try out some of their authors.