If you're going to buy one book..,
This review is from: Feature Writing For Journalists (Media Skills) (Paperback)
buy this one. This is already helping with many aspects of my course. It gives a lot of food for thought about how to construct the perfect feature starting from the initial idea until the end.
With a plethora of similar books available I would recommend this one (compared to the others in our uni library). It's new so the case studies are current which always helps.