Unfortunately it's been a long time since I first rewrote the essay into the article, and I no longer have the word document. The article itself is a faithful rewording, everything that was in my essay is in the article.
As for tips, the main things to keep in mind is staying focused throughout and always bring everything back to the question: start each paragraph with whatever point you're making, back up the point with evidence, and then show why the point is relevant to the question. So for example, you might start a paragraph by arguing that the US was partly to blame; then follow that up with evidence (For example, the Marshall Plan antagonised the Soviets, the Truman Doctrine, and whatever else you think backs up the argument), and then bring it back to the question, e.g. these actions by the US pushed the Soviets into the Berlin Crisis. Always keep the question in the back of your mind, so you don't go off on tangents and start talking about things that aren't relevant.