Before coming to Australia I made a research on how it is to arrive at Sydney International Airport. There I learned that it is better not to bring anything aside from my clothing and my gadget, no food of any kind. One thing for sure, of all the immigration entry procedure in a different airport that I have been trough...they are the most strict.
One of the best things about Sydney International airport is the convenience of going to different places, public transport is just around the corner. Buses, taxi, and train are just there arriving and departing on time. But taking a train from Sydney Airport Station going to your destination is sure more costly than the normal train ride coming from other station. They collect airport access fee of $12.80 for kids and $14.30 for adults plus the normal fare. If you are coming from Sydney Central Station to Sydney Airport they charge you just the normal fare of just around 2 or 3 dollars, But if you are coming from the airport to your destination expect a deduction of at least 15 dollars from your Opal card. (Opal Card is a prepaid card to pay for the daily public commute with the bus, ferry, and trains).
The best thing is that Sydney is a walkable city and whenever I am arriving at Sydney Airport, I just walk going to the nearest next station and I save at least $14.30. Watch the video on how I do it.