Both absolute beginners and experienced calligraphers will enjoy the Complete Guide to Calligraphy by Vivien Lunniss.
Exceptionally well-laid out and beautifully presented, the book (published by Search Press) teaches you how to master a total of 20 written scripts. As well as detailed explanation to the techniques each of the scripts is also accompanied by a full alphabet providing a valuable reference tool. The instructions are simple to follow but if further assistance or explanation is required there are also links to video tutorials.