One of the best tools for jump-starting a project to learn a second language is linguist Barry M. Farber's Learn Any Language (1991), a very tightly written, engrossing book loaded with tips and inspirational anecdotes.
Farber is a "polyglot", a speaker of many languages. His love of languages heated up after he almost flunked Latin in high school. At that point, he started reading a Mandarin Chinese language learning book. And soon after, he chanced to meet Chinese sailers training in Miami during World War II and made strong progress chatting with these native speakers.
Farber went on to study or sample 25 languages, including French, Spanish, Norwegian and Russian, which he studied in depth. He learned Hungarian while helping refugees flee Communism during the Hungarian Revolution. He picked up Indonesian as a young man while killing time with native speakers on a long boat trip.
At one point in Learn Any Language, Farber mentions that after entering the U.S. Army in 1952, he was "tested and qualified for work in fourteen different languages"
Farber's book methodically shows a language learner how to pick a foreign language, maintain the enthusiasm necessary to put in the study time, and wisely choose the tools and materials for learning. That last step is critical, since language learning materials are so vastly uneven in quality.
Some of the book's most valuable advice concerns how to exploit short, idle periods of time for language learning, like the commute to work, or standing in line.
One chapter delves into the use of memory-enhancing techniques or "mnemonics" to boost recall.
Farber's main point, however, is that anyone can become bilingual. It's the strength of the desire and the way one goes about it that make the difference.