A lot of really good advice here.

Then only thing I would think of possibly adding is with regards to seat selection. I would suggest to get an aisle seat, and that as close to the middle of the plane. An aisle seat is a little less claustrophobic than a window. Its easy to get up and walk around if needed, and chances are you'll want to get up and walk around on the LAX-SYD portion. The middle of the plane is because since pitch and roll are felt more at the extreme ends of the plane, the middle (over the wings) has the least. Try to avoid the rear of the plane if you can. Its noisier and sometimes has a 'tail wagging' shimmy to it.