I don't read book reviews...99.9% of the time, what some faceless reviewer I've never met has to say about a book is completely irrelevant to me.
I do have certain authors who I will pick up everything they write. Some I purchase, others I get from the library and may or may not purchase after reading them. Some I get exclusively from the library as I know their books are enjoyable but not worth spending money on.
I tend to read almost everything, so subject matter isn't as important. In fiction, I tend to gravitate toward certain subjects, but I'm still all over the map. The only subject I refuse to read are romance and Westerns. I simply find them poorly written and uninteresting.
My method for picking books at the library is to scan the spines to see if a title grabs me (or the topic stickers they place on the spine). Then I pull the book to scan the plot synopsis. If it seems interesting enough, I'll add it to the pile. I'm at the library every 1-2 weeks depending on my work schedule, and typically pick up 8-12 books at a time. Yes, I do read that much. I even retain what I've read.
I also will pick up a book if someone I know and trust recommends it. On the flip side, I have missed out on some pretty good books for entirely too long before finally reading them because someone I detest wouldn't stop raving about them. I'm like that.