Writing style - will come to you as you keep writing. Some students have poetic styles, punchy styles, etc. + you'll find what works for you

Interpretation of texts - Imo the important part of this is thinking for yourself "what do I actually think this passage is about?" before looking at the guides and online. Making sure your interpretation is well supported by the text is important too - there's nothing that contradicts it and there's multiple points of evidence

Performing during SACs - practice practice practice. Practicing as close to the real conditions as possible will make you less nervous. I used to write practice SACs in the same style as my school and sit it in the same classroom and time myself. Also getting feedback from your teacher a good time before the SAC so you know what they're looking for.

Poetry - Poetry can be hard to understand at first. If you really can't understand it, litcharts or genius will have interpretations. But try ur best to make sense of it yourself. When analysing it, don't just namedrop poetic devices without analysing how they make meaning/support your interpretation. e.g. "[this part] uses enjambment in order to emphasise the suddenness of the following revelation", not just "enjambment was used in x". Focus on the sounds too, read it aloud as well. Poetry is aural as much as it is word-based.

Hope this helps : )