This was a topic requested in my comments a while back. I said I’d do it so here it is.
The first way has to be recommendations. Books other people have read and raved about, old classics I was told about long ago and am only now getting around to reading and finally Amazon’s recommendations themselves.
When I first got back into reading lots only one source of these worked, the classics but I found as I read more and talked to others about what I was reading they started talking to me about similar books they’d read.
Another way I get good books to read is definitely Goodreads. It’s one of the best sites out there for a reader and it also keeps track of my massive to-read list as well as the books I’ve said I’d review for one reason or another. For that reason alone I’d recommend it but it’s also a great place to meet people with similar tastes, by joining genre groups or all sorts of other groups or following someone’s reviews who you’ve come to trust.
On top of all that Goodreads recommends books based on what you’re already told the site you’ve read and rated. It also helps you find books by the same author as you’ve already read and even get into contact with those authors too. Then there’s the giveaways. I’ve entered several and one won a paperback of a book I liked the look of recently. Plus all the review opportunities in the various groups. There’s always a thread somewhere with authors offering free ebooks in exchange for your honest review. It’s a great way to try new genres and new authors.
If Goodreads fails me (which is rare) there’s also a lot of facebook groups that try and connect authors and readers together to help them find each other and help them find books as well as many pages which share ebook links daily of their recommendations.
Finally, you can set up a review blog and let the books come to you. There aren’t enough good book bloggers out there to keep up with the demand caused by the currnet influx of authors so I pretty much guarantee anyone who starts one up and lets people know about it that plenty of books will come your way, to the point you’ll have to turn lots away.
I hope that helps with finding good books. I use a combination of all of the above and I don’t think I’ll ever get my to-read list to come below 100 books ever again.