The Make magazine published a special issue for 3D printing beginners. I received my copy yesterday and flipped through its pages quickly. It gives an excellent introduction about materials, file formats and 3D printing technology in general. Additionally, the issue provides valuable information about which kinds of printers you can buy and which ones are appropriate for you. So if you want to get started in 3D printing (or just want a good guide) be sure to get a copy.
For German readers: In Germany, you should get the Make magazine in selected book stores (and not at newspaper kiosks – not even the good ones at railway stations. I did ask and have only earned dull looks and the answer »hamwernich.«). I ordered my copy at amazon.de.