This will depend on you! What do you enjoy doing? What environments do you like? What is your budget?
If you want to live close to the campus, and you love a buzzing city environment, be prepared to spend more on your rent. If you prefer a slower pace, there are plenty of quiet suburbs in Sydney where you might feel more comfortable. If you enjoy outdoor activities, a room in a beach-side apartment might be the best option for you.
Sydney is a safe city, but it's important to live in a suburb where you feel safe. Choose a room or flat to live in that's easy to reach by public transport. Then, you won’t have to walk long distances or through dark streets to get home in the evenings.
It's a good idea to do some research before deciding which suburb you want to live in.
You can explore Sydney suburbs online via realestate.com.au or Domain.