How can we achieve, then, to write natural? I certainly do not have a model answer but I sure can offer my piece of understanding. You should read a lot, and write a lot. Like everything else, millennium old principle applies here with no exception: practice makes perfect. You should get yourself familiar with what you want to master. I’m sorry to end the whole thing with such a boring conclusion, but I can’t come up with a better one. See as many different sentence structures as you could and teach yourself with variety. Write down the ones that impress you most and consume them. Do your best to keep them in store so that when you need them, they will be at your disposal. Pile up your vocabulary, but never without context. Blind memorization of list of words is just silly. You should know when and how to use them, so when you run into a new word, you should pay an equal amount of focus to the sentence the word is coming from and not just the meaning of the word.
I work on business card English Korean translation, too.
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