Recommendations are often a factor, whether by someone specific or just generally having heard of a book, knowing it's considered very good, having read a good review, etc. When it's a book I haven't actually heard about before, which doesn't happen too often, the blurb is obviously the deciding factor, but obviously it's the title and to a lesser extent cover that lead me to reading the blurb in the first place - or not. Can't be swayed by a blurb I never read.

New in what sense? Every book I haven't read before is something new, in a way... still, whenever I pick a book way out of my comfort zone, I'd have to be in the right kind of mood to actually start reading it, and then get grasped from the start or else have to force myself to read on until it gets so interesting that I have to keep reading (assuming it ever does, obviously). It happens way too often that I get some book, often a big classic, from the library and end up returning it without ever having read even the first page.

It doesn't take much to convince me to get a book like that - actually reading it is another story. Just a matter of having time and having the inclination at the right time, I suppose.