Write to Sell is one of the best copywriting books available in terms of covering the basics clearly and concisely.
Reflecting his own background, Andy is very much focused on the nuts and bolts of creating high-performing, hard-selling content for commercial clients on a freelance basis.
The book covers focusing on the reader, planning, writing style and editing your own work. It also discusses writing for the web.
An excellent first read if you want to learn how to write commercially.