- Know some basic logic (e.g. if you think that P implies Q and you think that Q does not hold true, then you must think that P does not hold true either.)

- Read well structured essays

- Write (the difficult part). Since writing is pretty difficult, here is what I do: I write aphorisms (Nietzsche/Debord/Wittgenstein style) to force me to say the main proposition without deviating from my point. This forces me to state clearly what I want to say. At this point, the aphorism is nothing more than an assertion that needs to be proved with arguments. But my main proposition is already here and I can keep it in my mind while I develop my thoughts towards it. It's like a lighthouse.