China is a great place to learn Mandarin Chinese, even though English is spoken in bigger cities, speaking some Chinese will definitively help you.
Below are some useful links that could be useful to learn Chinese for preparing your trip/stay in Taiwan.
Probably the best source of podcasts to learn Chinese on the web.
Definitively the best place to learn how to write Chinese characters.
Definitively the best place to have 1-1 Chinese lessons with qualified Chinese teachers.
Definitively the best online English-Chinese dictionary.