You gotta move there for a summer, and speak nothing but Spanish. It's much easier to become fluent and learn Spanish when you HAVE to speak it to get around, get food, and meet people. It's also a good idea if you're planning to move there, because Mexico comes with its own share of problems, and you may find that you romanticized the country without getting to know the real Mexico.

Not to mention - it's a HUGE country, and every state is different. Different food, different culture. Some of them don't even get along. Mexico City is one way, Baja is another way, Northern Mexico is another way, Veracruz is another way.

Source: Am planning to live in Mexico.