This one's easy: Just dress like yourselves!
But since I do actually get asked this question all the time, I love to set everyone’s mind at ease about any uncertainties you might have: Generally I suggest you shy away from black (I know this is haaaarrrd for most Melbourne mums, and it’s especially important if we are inside), and 'words' or logos on tops, and keep everyone in the family to around 4 colours if you can. Small repetitive prints and patterns generally look fab, as do 'pop' colours in whatever shade you like. If you’re unsure, neutral tones always work well, and tones that match the season that we are in! You can see below, how well the creams and tans and blues look in a background of autumn colours.