There is no specific wording you need to use but whatever observation you are making about the excerpt, you need to make reference to the question. For example, if the question asked is 'describe how pitch is used in this excerpt', say you talk about melody, you comment on it and make a reference back to pitch, so something like 'the violin melodic line first plays in the upper range and then slowly decesding into some lower-ranged phrases, exploring the diverse pitch range of the instrument. Hope that helps
I would just get a list of buzzwords if you like that you can apply to extracts with reference to each of the concepts - especially contrasting ones e.g warm lower register contrasts the cold, harsh upper register etc.
I jot down bullet points and then write a little essay thing, maybe structured bullet points is better overall anyway.
I reckon first thing you should do is identify the instrument entry order, and then see where that takes you - range, layer, role, melody etc
This then leads to overall tonality and structure - structure often identified by dynamics etc.
If unsure just write aerophone, chordophone etc
If unsure of exact time signature it could likely be changing.
Just practice - that's the best way to get better, just do past HSC papers.