How do I resolve dictionary ambiguities when looking up words/phrases?
One way I use to "resolve" those ambiguities in a pinch is by using two dictionaries - one English to Chinese and another Chinese to English.

Essentially, when looking for a Chinese word corresponding to an idea you want to express, look it up in E-Ch dictionary first, then take all the results that you think you could use, and look them up again in the Chinese to English dictionary. Usually the subtle (or not so subtle) differences in meaning become evident in Ch-E translations. This works even better if you use dictionaries that have example sentences, ideally in both languages.

This 2-dictionary trick works for any pair of languages, best if one of them is your native or near native, so try to find dictionaries in your native one. Obviously it works the better the closer the two languages are, but Chinese is quite far, linguistically, from anything spoken outside Asia.

If you want to spend more time on this little research - look the Chinese word up in various online or offline corpora of sentences. Look up or Google the combination of this word and the one you're sure about - subject/predicate, "adjective"/noun and so on and see how many results you get - the more the # the more likely you got it right.

In the end, "usage" is all about context. These methods are quick (compared to asking on forums or reading a few books in Chinese ;) ) and dirty ones for establishing what word fits the context you want to use it in.