Purchase basic level Chinese language textbooks and audio materials and study them. It is critical that you listen to audio materials, because Chinese is a tonal language with many sounds that do not exist in English.
Enroll in a Chinese language class or locate a native-speaking tutor willing to help you. It will take you about two months of study at 20 hours a week to master the basic foundations of the language.
Move to China. This may sound like a drastic step, but immersion in a Chinese-speaking environment is the only way to develop fluency in the language. If you cannot afford to do this, you might consider moving to Chinatown in a large city such as San Francisco or Los Angeles.
Enroll in a full-time Chinese language school for foreigners. These schools are plentiful in large Chinese cities, and they can usually sponsor you for a long-term Chinese visa.
Make friends with Chinese people and practice your Chinese language skills on a day-to-day basis. In general, Chinese people are eager to befriend Western people, regardless of whether they can speak English or not.
Carry a pen and notepad everywhere you go. If you don't know how to say something, ask someone, record the pronunciation in your notebook, and review your notebook whenever you have a moment's spare time (while waiting for a bus or subway train, for example).