So, here are 3 essential books for your freelancer's ... or, better, solopreneur's library (even a single bookshelf would do).
These are some of the all-time classics I bought years ago and keep consulting from time to time. They just never age.
22 Immutable Laws of Branding (Al Ries, Laura Ries)
Yes, this is one of those oldies yet goodies. And no, this is not the ultimate guide to that trendy personal branding stuff.
Truth is, if you want to take your business seriously you need to get some insights about how business works. The 22 immutable laws of branding won't apply to each and every freelance business, but most (or at least some) of them can be easily adapted to most businesses.
Behavioural aspects of marketing (Keith C. Williams)
This book will come pretty handy as you walk down the difficult path of marketing your products and services.
Understanding the basic dynamics behind purchase decisions and finding out some of the processes that actually happen before, during and after purchase will help you grasp a deeper insight of the whole picture and boost your marketing efforts. This book might even prompt you to find out more ... this happened to me quite some time ago, and since then I'm completely hooked on the psychological aspects of marketing and advertising.
The advertising concept book (Pete Barry)
I bought The advertising concept book when it was first published in 2008 and loved it so much I bought the 2nd edition as soon as it became available earlier in 2012. The book focuses on concepts over design, which in my opinion is one of the most valuable tips you will find out there. This book is enjoyable, focused and realistic, providing the reader with some insightful food for thought on the most important aspect of advertising.
Bonus - extra book for you to enjoy:
Basic Economics: A Common Sense Guide to the Economy (Thomas Sowell)
In the book profile page, Barnes&Noble describes this as "a citizen’s guide to economics - for those who want to understand how the economy works but have no interest in jargon or equations."
That says it all, and I won't indulge on this further. This is an essential must-read for everyone willing to dive into the ocean of economics. Although this is not strictly a "marketing book" understanding how it all works will help you in getting a clearer insight on your overall business experience.