The task is to choose two colours that are opposite each other on the wheel and use them together. I had great fun going through my stash and putting together contrasting pairs, to see which I liked best, and decided in the end to use Blue-Violet and Orange-Yellow. The snag is, they've come out on my photo with the blue-violet looking bluer and the orange-yellow looking yellower!
Many thanks to everyone who gave me advice about how to stick intricate die cuts last time I used them - I used a cocktail stick and tacky glue this time and made a much less messy job of it. Not perfect yet - but that will take practise!