How do I write a strong argument?

The most important thing when writing is strong argument is that you clearly state your argument in the introduction and build on this throughout the essay to finally come to a coherent conclusion backing up what you first stated in the introduction. 

Both sides of the argument must be addressed in an essay as you must show that you have considered different points of view, but it is then up to you to show why one argument is more convincing than the other.

I would suggest the use of a Point Evidence Explain structure for each paragraph with a sentence at the end linking back to the question. This makes the point you want to agrue clear, demonstrates knowledge though some key facts to support the point and the explaination is your analysis of this point. Linking back to the question at the end encourages you to maintain a structured essay.