I often look on here and other book sites such as Goodreads. Also friends with similar reading interests are good for knowing you will probably be getting a great read.
But if I like an author, I tend to look for their next books. It doesn't always work out though. I bought 'Eeny Meeny' when it was on a kindle countdown - absolutely cracking read so I couldn't wait for the next book by the author. I bought it as soon as it became available and dived right into it. But I was completely disappointed and ended up abandoning it about a third of the way through.
In contrast to that, a friend of mine recommended 'Gods Inc' by Sarah King. I'd never heard of the author but the book was free on amazon so I 'bought' it and LOVED it. So when her next book, 'What Laura Saw' came out I bought it and wasn't disappointed. Loved that even more
I have read and enjoyed almost all of Stephen Kings earlier work, but haven't been in the mood for a horror book for a few years now. I like psychological thrillers the best.
A while ago, I gave up on reading only well known authors and have taken a chance on quite a few indies. I haven't regretted that one bit. I didn't realise what I'd been missing. Some are rubbish, obviously, but there are some real gems amongst them.
However, the one I really want to read right now is 'I let you go', but I'm waiting for the price to drop. £6.99 for a kindle book is too much IMO. I'm currently reading 'Gone Girl' because I want to read the book before watching the film.