How do I start analysing language use in texts in exams?

While the texts are unseen, you can plan your exam analysis technique before you get into the exam. The AQA mark scheme in 2017 does a good job of breaking down what's important to include. First, close analysis of the texts themselves, which provides opportunities to pull quotes and use terminology. This usually feels more like a scientific analysis of the text, and may feel really specific. Second, evaluating the use of metaphors, representations and the influence of context on the text. This will be addressing the broader tone of the text, exploring how the text sits within society and what effect it has on the audience. The important thing to remember when you are doing this is try where you can to connect everything together into a cohesive argument.
If you're writing about two texts together, make sure to also form connections and point out differences between the texts and the way they're written. You can integrate these into the essay's paragraphs, rather than splitting them up. When you plan the essay, make sure while each paragraph address a separate broad topic, you're also going into a significant amount of detail with the examples you provide.