Like many foreigners, Giles Murray has parlayed his experience with the Japanese language into big bucks - ok, well at least just a book. But before you run off adhering to everything prescribed in this book, PLEASE read this review. It is well worth your time.
There seem to be some good ideas in this book. One that I particularly found helpful (one that I had already intuitively realized) was the hint covered in Chapter 6, "The Synonym Generator". Basically, Mr. Murray recommends that one possess a vast array of words to describe a certain feeling or concept. That way, if one gets a mental block and is not able to remember one expression, they can dip into their bag of tricks and express themselves in another way. Another chapter where Mr. Murray discusses how to "describe your way" out of a jam when you can't think of a word in Japanese is EXCELLENT advice. This is more or less a survival Japanese tactic, but comes in handy for advanced students as well. Rather than sitting in a conversation with a dead look on your face, it's best to dumb it down, if for nothing else, to keep the conversation moving.
What I caution you to NOT follow, however, is Mr. Murray's advice regarding gairaigo, or loan words. There are thousands and thousands of directly borrowed and some slightly altered English words used in the Japanese language. While every student should become aware of their existence and correct usage, you should ABSOLUTELY NOT use them with the frequency that Mr. Murray suggests. You will do so at your own linguistic peril. For, you see, American (and British, Australian, etc.) students who rely on these words tend to not learn the Japanese equivalents. They also tend to use a disproportionate amount of them in their speech. I heard a figure one time saying that a MAXIMUM of 13% of a Japanese person's daily conversation is composed of loan words. This is a maximum, mind you.
So, not only do you limit your proficiency by depending on loan words, but you also send a signal to the listener that you don't really know the traditional Japanese versions. Furthermore, Japanese tend to linguistically discriminate against foreigners by using these loanwords with them because they don't believe they know the Japanese equivalent. I recall one time being at a station and the manager yelling to me to "chenji (change)" my ticket instead of telling me to "kaeru (change)" the ticket. This is linguistic discrimination - there's no other word for it - and following Mr. Murray's advice will cause Japanese to speak to you with a vocabulary unnaturally heavy in these words.
Don't get me wrong. There are times when they are useful, but DO NOT use them to the extent he recommends. For example, use the word "kyanseru (cancel) suru" for cancel, but DO NOT use the word "happii (happy)" for "shiawase (happy)". The message would get across with the former, but you'll also be displaying your ignorance of TRUE (yip, I said it, Mr. Murray) Japanese (ie kango and wago).
Mr. Murray, who happens to be a copywriter (and copywriters are NOTORIOUS for overimporting English into Japanese), may use these words to a grotesque and unnatural degree, but you shouldn't. Consider yourself warned.