Hey,
I'm assuming you finished your HSC already so this is probably not useful for you
but hope you did well !! For those of you who are planning to do Chinese heritage (renamed as Chinese in context), what i recommend for the personal investigation is the following (just some suggestions, hopefully helpful LOL):
1. Use around 3-4 texts (preferably different text types, e.g. interviews, online articles, newspaper articles, TV programs, novels, etc)
2. FOCUS your investigation on discussion of the texts in relation to your chosen topic (if your investigating/researching about the One Child Policy for example, you should refer to statistics/figures or whatnot from your chosen texts to make your personal investigation thorough, detailed, showing extensive knowledge)
3. Techniques are not extremely important, but you do need to try and use as many idioms, figures of speech when you are answering the questions on the day. This is part of the marking criteria i believe.
4. Preparation should not only be focused on writing answers to sample questions, but rather more so making sure you have extensive knowledge of your topic and texts (they can ask you any questions on the day, so do not expect them to be straightforward). Make sure you have a personal opinion on the topic (I remember during my interview, i was asked "what is your opinion on this [chosen topic]" and "how would you solve this issue etc"
5. With regards to choosing a topic, make sure you do one that is original and closely linked to what you have been studying in class/syllabus. (Western/Chinese approaches to dating/marriage, education systems are all pretty cliched topics and have been done THOUSANDS OF TIMES. I know this because my teacher is a HSC marker, and told us that many students choose these topics. If you want to do well, it would be better to choose a topic that's not as mainstream and popular)
6. Not 100% sure about this but i think the interview is marked BASED on your research/ideas presented/ how WELL you answer the questions, so don't waffle (i did that a bit) and go off on tangents. You are losing precious time and gaining zero marks for this. So be concise with your answers. Also, they will look for sophistication of language, the vocab you use as well as the grammar and sentence structures. Pronunciation, clarity and intonation is also pretty important. (PLEASE SEE ATTACHED FILE)
D.H.