There are a few types of Australian coinage that are relevant to this topic.
Pre-decimal coins and banknotes.
Royal Australian Mint (RAM) Decimal Issues.
Pre-decimal coin issues such as the penny and shilling ceased to be circulating currency when Australia changed to the decimal system in 1966. Of the RAM issues there are circulating coins that you would find in your change and what we call NCLT ‘non-circulating legal tender’ issues of coins. The Perth Mint also releases coins that are NCLT primarily for the collector market. This NCLT is often different in size, weight and composition to that of it’s circulating cousins but the Mints’ also produce coins that have reverse designs that weren’t intended to enter circulation but appear to be just like the coins you find in change.
Firstly when thinking about starting a coin collection you must decide where your interests lie, is it for fun or investment? Then maybe you need to consider your budget. Some issues can be very expensive due to rarity, mintage or condition. With that in mind you could start a coin set striving for a coin for every year,denomination, each monarch or a set of error types. The list is endless really with the key being enjoyment. A piece of advice would be when buying choose wisely, research prices and buy the best grade you can afford at the time. Just collecting interesting coins out of your change can be fun and a great way to introduce the kids into the world of collecting.