One thing so many people skip over is the following; You get your marks for your analysis NOT identification! Let me elaborate slightly, you could identify every technique and persuasive device under the sun and not get full marks. It's all about identifying, analyzing and then discussing what the intended effect was.
Do everything you would normally for the introduction, then try to focus on how the writer has constructed their argument.
Example, The article has an opening, 3 main body paragraphs, then conclusion. Your analysis should have an introduction, three paragraphs of analysis (One key argument = 1 body paragraph) then your conclusion.
In each paragraph Identify the argument technique (What was used constantly throughout the paragraph) (e.g Rhetoric, = Identify, analyze, then intended effect.)
Example body paragraph : "Alliteration was predominantly throughout the first paragraph, "example of alliteration", the use of the word 'x' and 'y', both highlight and enable the readers to be consciously aware of the severity of their actions, in doing so readers are positioned to feel a strong sense of justice. The use of Rhetoric "Example of rhetoric", "Analysis here", in doing so "intended effect here.
Do you see the pattern yet?
In 1 body paragraph there should be;
1. 1x Argument technique (what's supporting the argument, and used frequently), 3x Persuasive devices; You then included an example, analyze it then state the intended effect.
Doing the above x3 will get you a very solid analytical essay!
This might be a bit confusing so please ask any questions! I really hope this is helpful in someway, but remember most people lose marks by forgetting the intended effect which is the biggest part!