The first step is to estimate the shipping cost. This is the most difficult thing to do with any order since you most likely don't know what the exact weight of your order will be. It is even more complex than just working out the total weight because some shipping methods are based only on weight, while others are based on both weight and volume. The best way to estimate the shipping weight and cost is to make use of the shipping cost calculator.
If you enter your best guess of the box dimensions and weight the calculator will tell you the various option you have for shipping. It is important to enter your postcode (if you live in Australia) as the total price as this will affect the shipping cost for some shipping options.
Don't worry if you don't know the exact weight and size. In the end it doesn't matter what you or we estimate as you are only charged based on the actual shipping weight and volume.