For writing exercises, I usually just start with an idea or outline and not write it completely in my native language and translate. I do this for two reasons. First, my vocabulary in English will obviously be much deeper than in my target language, and my primary goal in speaking another language is to be able to express myself clearly, not necessary wordsmith the most eloquent words that I can come up with. By avoiding this intermediate, native language writing phase, I'm not detracted from the exercise by trying to figure out more "sophisticated" words that I may not have at my disposal in my target language.
Second, by not translating, I am less likely to do word-for-word swapping that ends up forming incoherent sentences because I am applying an English sentence structure to the target language, resulting in really awkward wording. I think this is one of the pitfalls of relying on online translators like Google Translate to form sentences in one's target language.