Sometimes it pays to start off in an area where gold is commonly found - not heaps and heaps but where you can almost gaurantee to find some - the Lindis is a great place and also Arrowtown. Watch others who seem to know what they are doing and where they are looking - dont be afraid to ask for pointers - ask them to show you what they consider is the most likely spot to find a colour or two. Nearly everyone will be happy to give you helpful hinters and once you get the hang of where to look and how to go about it then you wont look back. Once you start finding colour and know the sort of spot you are most likely to find it then you can progress.
If it is a lot of gold you want or larger nuggets then you have to take the next step - really do your research on the place you are about to go - what to expect there. Know where the gold is likely to be found there, old wash, river bed, cracks, crevices, that rusty strip of wash high on a cliff, that band of iron sands running through a bank, under the peat - get to know that particular gold field and where the gold was found on it, the type of country it was found in...get to learn to read the land...all are hints to success.
Where I go colour is indeed a rarity so that it is nuggety material I am most likely to find or larger bulkier flakes - if you do not know the land and how to read it, if you dont know the spots where gold is likely to be found then in the areas I go you simply will not find it...but if you get some practice in the Lindis and Arrow Rivers then you will get to know where it is likely to be found and can then translate that to other locations where the gold is bigger but colours not near so abundant - Hmmmm - I hope that all made some sort of sense!
Another thing to is to always take shorts to paddle in the creek, always take a glass bottom box and a bent screw driver and tweezers and clean out even the tiniest of cracks in the Lindis and Arrow rivers. In other rivers as well...you might be not only surprised but amazed at what you find.
Good luck!