Hi! In my case, word choice is most difficult while grammer is not that hard as is typical Japanese. The second is article (though this is one of essential grammer...).Everytime I write in English, I always have an ambiguous feeling about whether this word is correct and where sI should put 'a/an' or 'the'. Dictionaly certainly does not give me any answer. All I need is "learning by doing" and having a good teacher!
Hi there. Yeah, articles and prepositions can be really difficult, even for native speakers. I would recommend reading as many novels in English as you can, as this might help give you a sense of what sounds right.