Over the last twenty years, I've taught myself a little German, a little Czech and a bit more Italian. I wasn't very good at any of them, though I managed to get around, buy meals and not get arrested in Germany, Prague and most of Italy. Along the way, I bought a lot of different software, language courses, dictionaries and phrase books and looked at a lot of book and websites about learning languages.
Most of it was a waste of money and time. Given that all that stuff was designed or written by "experts" I figured I was the problem. I decided I just didn't have an "ear" for languages and would never be better than a ten day tourist with a phrase book and an atrocious accent.
A couple of years ago, I decided to learn Tibetan and I started as I had in my previous language acquisition attempts. I wasted a lot of time, got stuck in the same ways, made many of the same mistakes. If anything the proliferation of web sites that allegedly support language learning made my attempt even more muddled as so much of the advice seem contradictory or just plain dumb. I seemed to be on track to have another two hundred word, twenty phrase vocabulary that wasn't good for much but ordering meals, finding a bus station or asking about the weather.
Then I found this book. It is the one of the two most pragmatic and useful primers on learning to productively read, write and speak a language that I have found. (The other is Speak Like A Native: Professional Secrets for Mastering Foreign Languages) Written by two people who have been learning and teaching language for decades, it is filled with useful advice, methods and suggestions for acquiring a new language. As importantly, the authors talk about what doesn't work and why, information I found incredibly helpful. The authors focus on how to develop real world fluency in speaking, reading and writing, with an emphasis on self-teaching. They make it clear that fluency is a matter of work rather than "a talent for language" and offer lots of practical out-of-classroom ways for acquiring it.
The book also has an excellent table of contents and index, along with a set of appendices of grammars and lexicons that can be used to as models for developing your own learning materials. It is an easy to use reference for problem solving and handy for learning new ways to approach tasks like vocabulary learning. Above all, it is pragmatic: the authors talk about what works and what doesn't, how long things take, how much time things take. An interesting feature of the book is the author's decision to present their methodology differences, so for example, they offer two different approaches to learning basic grammar.
While I may not agree with all of their opinions or use all of the methods they offer, I have found Gethin and Gunnemark's "Art and Science of Learning Languages" to be indispensable. It has fundamentally changed - and improved - the way I study language and it shows in the progress I am making in learning Tibetan.