If you're a serious writer (or want to be a serious writer) then you need this book. It covers pretty well everything you need to know about 'how to' and all the contributors are seasoned professional writers. The best thing about it is the list of additional resources/reference books that appears at the end of each section. A heavyweight publication. You should acquire it, even though it's not cheap!
This is the best book on CW that I have read so far. It is comprehensive and gives great insight into all areas of CW including screenwriting, playwriting, writing for radio and novel writing. There are loads of resource addresses for you to explore - Buy it - you won't be disappointed.
Just read lots. This is not essential although it does offer some good advice. I would recommend trying to copy authors whose style you like as Robert Louis Stevenson did. There are hunners of handbooks I don't think Irvine Welsh or Plato had one.... Maybe their shelves were full of them. Stacked !