1. Offer a reasoned argument correctly. Actually if you state the reason for your arguments correctly there is no wrong answer.
2. Keep it simple. Less is more.
3. If you can, incorporate some independent thoughts into your answer.
4. Discuss your answer to yourself.
5. Don’t write compulsively.
6. Write a draft on WP and correct misspellings and any errors in logic. Write clearly, in proper English. Avoid slang and broken phrases.
Here is an example of a short paper. And here is another. Obviously, you are not writing a paper, but a 150-word comment can be considered a sort of mini-paper. Here are some pointers regarding phrases:
You can state a position by defining it. For example: “Libertarians believe that…” of if talking about a person: “Animal right advocates suggests that...”
If you want to suggest a hypothetical situation of your own, go like this: “Suppose that,” or “Imagine so-and-so,” or “Just for the sake of argument…”
Phrase your views properly: “I believe that” or “I suppose,” or any other similar form.
Whenever you compare, you can use, “on the other hand, Locke holds that memories are…”
For conclusion, use: “Therefore”, “As a result,” “Thus,” “In conclusion,” etc.