There are so many pullouts and sights to see along the Great Ocean Road, that you may find yourself falling into a 'yet another spectacular vista' fatigue. Is it worth pulling off the road for another cliff drop, another gorge, or another arch? Make sure you plan your trip, so you can skip some attractions if you need to, but don't miss the truly amazing ones which are generally within the area between Lorne and Port Campbell. And, of course, you have this wonderful guide to help you along the way!
Stick to the speed limits. This is one of the most frequented roads in Australia, especially by tourists, and the Victorian Police are well aware of that. There are several places along the Princes Highway where you can get booked, especially as you head out of Melbourne, and the fines are hefty by any standards. Strictly follow speed limits even if you are in a rental car as they will find you wherever you are. Aside from this financial disincentive for speeding the more obvious and important one is that speeding is not good for staying alive. Please drive carefully and safely!
If you are not a strong swimmer or are inexperienced in the surf, then ONLY SWIM IN PATROLLED AREAS. You will get into trouble in the water if you do not follow this advice. There are powerful currents that can rip unsuspecting swimmers out to sea in seconds at many of the remote and un-patrolled beaches along this coast. You can swim safely whatever your experience, as long as you do it under the watchful eye of professional lifesavers.