What do you look for....

If it is a genre I like.  If it's by an author I like.  The title sounds interesting.  The plot summary sounds good.

I used to read too often to pick a book because it happens to be a favorite author. I read faster than any said authors could write and publish. But...
Plot summary=reading the back of the book and title are certainly a couple of ways I choose a book.

I hardly ever pick a book someone suggests. Odds are good I won't like what I read. haha
But I do listen to what is said because when someone likes a book enough, they talk about in detail. If I ask the right questions, I am practically read to and so reading the book suggested is moot.

I read a book once and never read again in most cases because memorizing what I read is something I automatically do and its pointless to pick the book back up. I can tell you the story front to back with very little change in wording. I wish I could have done that in school. My grades would have been much higher.

Because of that, when I pick a book to read, I look at the front of the book and read the readers notes often in a book and then I read the last page of the book.
If the book isn't in the 'genre' I usually read, this helps me decide if I can really get into the book.