Ramjet is right - if you are doing your job you should be getting the bottle caps and pull tabs because on most detectors there is almost no difference in detecting a gold ring or earring. You might pull 100 or even a 1000 bottle caps but you will eventually find one! My son and I have been detecting for just over 12 months and we have found plenty.
Lesson #1 - pin pointer
Lesson #2 - location, location, location - you may never find good treasure if you don't walk over it. You need to do some homework on the best place to hunt in your area. Sydney is an old place so there is bound to be lots of parks that contain goodies - maybe Parramatta or somewhere that has some history. This is the hardest lesson to learn but once you do you will see your finds pics grow and improve in quality.
Like any hobby - the more you do it the better you become - keep on swinging!