Unlike some of my blog-mates, I haven't been writing fiction all that long, but in the past year and a half or so, I have found that reading isn't just for pleasure anymore (although it still is very pleasurable).
In my quest for a perfect first chapter for my own manuscript, I tend to browse stacks of YA books in the Borders, just reading the opening sentences. I also like downloading free chapter samples to my Kindle (Yes, I confess I have one and love it.) for the same reason. Of course, if the first page is very engaging, I end up hitting "buy now" and my research costs me money. I guess that is a sign the author did a good job with his or her opening paragraphs and is worth studying.
Carmela Martino encouraged us in a writing seminar to pick an aspect of writing, like back story, and track all instances of it in a novel. I do mentally make note of style, setting, things I like/dislike, but I admit that I haven't yet made my first attempt at this. I intend to try it because it makes sense. If one can see how back story is woven throughout the whole narrative, it might not be as tempting to get all the detail out up front, for example.
I also really enjoy reading what my critique group writes for our discussions. I find that I am learning a tremendous deal from their writing choices and the comments other people make.