I think to travel in China, it's worth learning a little of the language, at least to read pinyin and some street signs, as well as the basics such as numbers.

You don't need to give away the fact that you know Chinese though - e.g. when shopping, if you know the numbers, you can keep your ears open for the "original" price (say if they're discussing with a co-storekeeper) if the vendor's trying to rip you off!

Some good online guides for beginners (who only want/need a few basics) are:
http://www.travelchinaguide.com/essential/language.htm
http://www.ecchinese.com