As a chinese,I have a difficulty in writing an idiomatic article.Sometimes both grammar and words are used correctly, but it is still quite different from the works written by the native English speakers.
That will come with time and contact with native speakers. Try to listen and read actively for what they use and follow them if you want to use the language idiomatically. Alsom be careful when taking things from dictionaries as they will often give you a word, but not necessarily the most idiomatic one.
As a rule of thumb, you can say: if it appears on Google, it may be unidiomatic; but if it doesn't appear on Google at all, it's almost certainly unidiomatic.
Another good site to check usage is http://view.byu.edu - enter a word or phrase and it will give you examples, you can also choose a word and a grammatical category, so you could look at a word plus, say, prepositions, and all the examples come from real texts.
How to compose an idiomatic English article 
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